The native Africans of Liberia and Sierra Leone have arguably had to deal with the brunt of the consequences of this movement. Liberia was established as an American colony to send back ex-slaves from the United States, while Sierra Leone was established for the same reason as a British colony. I can speak to Liberia and hopefully someone else can chime in about Sierra Leone.

The descendants of ex-slaves in Liberia are generally referred to as Americo-Liberians by Westerners and Congo or Congau by West Africans.

In the first half of the 19th century, the American Colonization Society (the organization primarily responsible for the ‘Back to Africa’ movement) sent at least 4,500 ex-slaves to Liberia. It is estimated that only about 1,800 survived. Among these was a man named Joseph Jenkins Roberts, who encouraged a movement for Liberian independence and became president of the country when that independence was achieved in 1847. Although independent, Liberia continued to receive a large amount of support and protection from the US government.

From 1847 until 1980, the government of Liberia was controlled by Americo-Liberians. To some, this leadership was good. William Tubman, considered the father of modern Liberia and its longest-serving President, served during a period of overwhelming economic growth. He improved the country’s infrastructure and successfully lobbied foreign businesses and politicians to invest in the country.

Their leadership did not sit well with most indigenous inhabitants of the region. Americo-Liberians made up a very small amount of the population (around 5%), and many of their policies encouraged what was seen by many as the exploitation of indigenous tribes, particularly on rubber plantations. They also didn’t have the right to vote. Americo-Liberians refused to marry with native Liberians, viewing them as ‘racially inferior.’ The economic support granted to Liberia did not extend to them, but only to Americo-Liberians. Because of this, they were much wealthier than the natives, leading to widespread animosity. It is difficult to avoid noting the irony of these policies being promoted by people who themselves had recently been victims of similar policies. Similar to White Americans, many Americo-Liberians argues that the native populations were not beyond redemption—they could become civilized through conversion to Christianity and adoption of Western values.

Presidents since at least the early 20th century had been trying to deal with the increasing divide between Native populations and Americo-Liberians. President Arthur Barclay asked for better relations between the two groups, but very little was actually done to achieve this. Tubman attempted to bridge this gap during his presidency through a policy known as ‘National Unification.’ It is celebrated today on May 14th in Liberia as ‘National Unification’ or ‘Integration Day.’ Tubman extended the right to vote to native populations as well as women. Society became more integrated as native Liberians began to move to Monrovia in search of work and work alongside Americo-Liberians (previously the populations had been mostly separate). This integration also brought increased hostility as the economic disparities between the two groups were put on full display.

Tubman is a controversial figure. After an attempted assassination in 1955, he became increasingly authoritarian. Although the policy of National Unification may have seemed to be working during his presidency, after his death in 1971, things began breaking down. William Tolbert succeeded Tubman.

Tolbert was in many ways caught between a rock and a hard place. A member of one of the wealthiest Americo-Liberian families in the nation, his ascension did little to appease the still-frustrated native populations, since it highlighted even further the economic disparities between the two groups. Tolbert tried to appease them and further the policy of National Unification by speaking Kpelle, an indigenous language, and bringing in more indigenous people into the government. This in turn, led to extreme anger from the Americo-Liberian population. Tolbert’s own cabinet hated the idea. Tolbert attempted to make the country more democratic and less reliant on the West, a policy which was popular with some indigenous groups, but not with the Americo-Liberians who feared their hold on power would be lost. All this came to a head in 1980, when Tolbert was assassinated in a coup by Samuel Doe, effectively ending nearly 140 years of Americo-Liberian rule.

I don’t really want to go into the Liberian civil war because it would be too lengthy and go too far from the question but suffice it to say to this day there still remains a divide between the population of the descendants of ex-slaves in Liberia and indigenous populations.

The short answer to your question is—the vast majority of West Africans did not like this movement since it forced a repressive system of government upon them run by people who were seen by West Africans as foreign colonizers.

In a more recent context, the historian Kevin Gaines's 2006 book on African-Americans returning to Ghana during and after the civil rights movement deals with the reactions of West Africans. Saidiya Hartman's Lose Your Mother and Paulla Ebron's Performing Africa also consider West African responses to African-American heritage tourism and "return to Africa" narratives in the last fifty years--and there are other works by anthropologists and historians that do so. (I'll also recommend the novelist George Lamming's Pleasures of Exile, which includes some commentaries on being a West Indian resident for a time in Ghana and his observations about other Black expatriates and exiles.) Additionally, the historian James Campbell's Middle Passages is a great comprehensive history of African-American returns to West and Central Africa and various African reactions to those returns over time.

I think in the recent era, one common summary of West African reactions to returns out of the African diaspora might be that they have been a mix of bemusement, appreciation, bewilderment, gratitude and occasional mild irritation. Since the 19th Century, some African-American returnees have been unsettled or surprised by the fact that they have been read as "foreigners", even as "white foreigners", rather than kin (Langston Hughes talks about this in his autobiography, and Hartman much more recently struggled to process the same reaction). But that is where all those feelings among West Africans come together--a pleasure that there are these travellers who so intensely desire a feeling of connection and who are often so flattering in the way they express that desire coupled with a modest amusement at how little they often seem to know about the place they've come to--and the irritation that can follow when the new arrivals clumsily elbow local people out of the way or try to tell them what their history and cultures really are or ought to be. (The scholar Henry Louis Gates Jr's first travel program on his African journeys created some modest annoyance for this reason, most potently when he picks a fight with one of his West African hosts about the legacy of the slave trade.)

I think as Black heritage tourism has become more economically important, the sense of mild puzzlement at diasporic returnees has faded and more familiarity with returnees and their interests has developed. More recently, too, I think West African artists, scholars, writers, performers, etc. in Ghana, Senegal, Nigeria, etc. have developed more confidence in partnerships with diasporic collaborators, which has brought short-term and long-term returnees a closer sense of belonging and connection.