I may be presenting the situation a little simply here, as my study of this issue was merely as a background to the revolution. My sources stem from the compilation textbooks Liberating France by J Fenwick and J Anderson, as well as France in Revolution by M Fielding and M Morcombe. Both of these books present information with a level of interpretation overlaid, but given that this is pre-revolutionary, and both books are focussed on the revolutionary period, I shouldn't have too many problems with bias. An academic may be better equipped to answer your question and provide additional information and sources.

Necker became Director-General of Finances, effectively finance minister, in 1777. The French crown's financial situation was quite dire, and my sources place a large portion of the blame for this on a tax system that did not collect from most large landholdings, as a result of their being estates of either the nobility or the Catholic Church, and administrative inefficiency caused by tax farming and patronage. At any rate, the situation was bad enough that Turgot, Jacques' predecessor, advised strongly against intervention in the American War for independence, saying that "the first shot will bankrupt the nation".

Jacques, as Director-General, was unable to solve the revenue problem sufficiently that the Crown could afford to intervene, principally because those who would need to approve of the removal of the tax privileges that reduced revenue were those that benefitted from such tax privileges. It is also important to note that information regarding royal finances was both complex and difficult to acquire, as taxes collected in the crown's name were not necessarily taxes the crown recieved- tax farmers would collect pay expected revenues in advance and keep any profit when they did collect taxes. This obscurity meant that the court outside the Royal Ministers may not have been aware of the state of the royal finances, making Jacques' arguments to equalise certain land taxes less persuasive. As a result of these two factors, Jacques borrowed money to pay for the war. As expenses on the war increased, credit gradually dried up. To acquire more credit, Jacques raised offering interests higher and higher to attract more creditors. By 1781, the interest the Crown was paying was in the hundreds of millions of livres, with total revenues less than a billion livres.

Now- to answer your question, Jacques had multiple motivations for publishing the compte rendu. Firstly, his attempts at reforming revenues had alienated some of the court, including the King's wife. A favourable account of the crown finances would ostensibly improve Jacques' situation at court and improved his popular image. Jacques was pursuing an official position as Royal Minister, and support at court would improve his chances. Secondly, if the crown's finances appeared to be in the black, it would be less likely to go bankrupt and thus default on interest owed. This means that the compte rendu encouraged lenders to continue financing the French deficit. As to his real motivations, I'm not sure a primary source exists to tell us why Jacques actually published the compte rendu.

Jacques didn't get his position as Minister- the rest of the ministers advised against his appointment and Jacques' publication of the rendu soured his relationship with the rest of the government who were savvy to the fraud. He left government soon after the book's publication.