When I use the convert function I will often do a hundred plus at a time. The convert window that shows how many are being done at the bottom left shows, for example 97/120 but can’t show 102/120 as there are only six spaces so it looks like 102/12. If you corner drag the box to enlarge it the counter space stays the same size. There’s loads of space to extend the box a bit, I wouldn’t think more than three figure numbers would ever be needed. Not a necessary change but it would look better. It could be the same as the email/web copies box that says Processing and the 102/120 bit just shifts along to make room.
The reason I do large number of file conversions is that I use Zerene stacker that can’t use RAW files and using QI’s converter means the auto RAW adjustment / filters can be incorporated into the TIFFs. It works very well.