I have been working on some drawings recently where millimetre accuracy is needed and have noticed the rounding seems to be adrift if you use maximum accuracy in the dimensions. It's difficult to point a finger at where the problem is. I know the software will use mathematical rounding, which is frustrated by the transition between binary and our use of metric or imperial numerics, but I do sometimes wonder if AC's calculation accuracy has been dumbed down to speed up the user experience. It's a difficult call for GS as they need to cope with objects that may be a threaded bolt up to a city plan, yet still achieve optimum feedback against dimensional accuracy. The other aspect I struggle with is the use of guide lines which since their introduction have been prone to generating false points unless zoomed in close. I guess this doesn't help much, I do however empathise with your accuracy & trust issues.
Apple iMac Intel i9 / macOS Sonoma / AC27UKI (most recent builds.. if they work)