Quite right.
The Americans used the Charlevilles as models for their own long arms, notably the Model 1795, which, in various forms and contracts, served as the main US arm until it was replaced by the Model 1816.
The .69 caliber was probably preferred because a one ounce ball will mic out to be .69 caliber (16 gauge). It is easier to require militia to carry accouterments for a "one ounce ball", so it is a simpler standard to use, as well as permitting the men to carry more rounds of ammunition.
“... The .69 caliber was probably preferred because a one ounce ball will mic out to be .69 caliber (16 gauge). ...”
16 gauge corresponds to a bore size of 0.662 inch. 0.69 inch corresponds to a bore size of 14 gauge.
Modern users (often reenactors) load French pattern muskets with various ball diameters, usually 0.68 inch or smaller.
An undersize ball was essential to sustained fire.
Continental Army ordnance regulations specified a ball diameter of 0.627 inch for French pattern muskets: plenty of “windage” - empty space - to enhance ease of loading even if the musket bore became fouled after several firings. Specified charge weight was 187 grains of powder: enough to prime the pan, while reserving enough for the main charge to give the loose-fit ball a pretty healthy initial velocity.