I recently found out about this intriguing fact, but sadly there is not much reading available in English. What was the Soviet plan behind this coup and were there other coup attempts directly organized by the Soviet Union in the interwar period?
https://en.wikipedia.org/wiki/1924_Estonian_coup_d%27%C3%A9tat_attempt
I unfortunately can't answer your question about Estonia, but I can note another failed coup attempt by the Bolsheviks: a 1920 plot to overthrow the Democratic Republic of Georgia.
Georgia became independent in the aftermath of the Russian Revolution, and was dominated by the Mensheviks (the more moderate branch of the Russian Social Democratic Labour Party; the Bolsheviks were the extremist group there). They didn't like the Bolshevik policies in Russia, and worked to suppress them in Georgia, actually outlawing Bolshevism. This wasn't a big deal, seeing how the Bolsheviks were hugely unpopular in Georgia (their numbers were never much more than the low thousands, while tens of thousands were self-declared Mensheviks). Even so there were local agitators, and the Bolsheviks were aiming to take over Georgia.
Thus a plan was hatched for May 2, 1920. The previous month the Red Army had invaded and occupied Azerbaijan, conquering the country in about 11 hours and not firing a shot. With this military force right next door, the Bolsheviks in Georgia asked for help to lead an insurrection there, and ultimately take over.
A date was set: May 2, the day after the May Day parade, which was a huge socialist event and would be sure to cause some disturbances between the competing groups in the capital Tbilisi. This was also chosen because that night the Georgian leadership would meet at the Soviet (meaning council). The plan was for the Bolsheviks to surround the building and force the Mensheviks to give up power, and then invite the Red Army in to ensure there was no chance of a counter-coup.
This proved an unmitigated disaster. Not nearly enough Bolsheviks showed up, and a group of girls from the Young Communist League was late, further reducing their numbers. By the time they were ready to do anything, the Mensheviks had left, and the Bolsheviks were instead arrested or scattered. A few did try to attack the military college, but that ended in either death or arrest.
This was the last attempt by the Bolsheviks to overthrow the Mensheviks. This was because a week later, on May 7, the Treaty of Moscow was signed between Georgia and Russia. It established diplomatic relations between the two, and Georgia agreed to legalize the Communist Party in exchange for no overt interference in their internal affairs from Russia. Of course this only led to further Bolshevik propaganda, and in February 1921 the Red Army simply invaded and defeated the Georgians, occupying the country.
I don't remember this being referenced specifically, but you'd do well to read through Stephen Kotkin's recent 2 volume (of a projected 3) biography of Stalin. He covers every aspect of early Soviet foreign & domestic policy in volume I: Stalin: Paradoxes of Power, 1878-1928.
Broadly speaking Kotkin considers that Stalin himself was a true believer in the Revolution and genuinely believed that it was necessary for the Revolution to spread beyond the borders of traditional Russia. More importantly, Stalin and many of the early Communists were convinced the West/capitalist countries - particularly Germany - were getting ready to launch an all-out attack on the Soviet Union. Any strategy in the Baltics would have had more than half an eye on providing a buffer between the Soviets and Germany.