I think that after you select MyUtils, you will have to type a period for the autocomplete to begin suggesting things that begin with MyUtils.. Other than that, I would expect it to work as you desire.

I don’t think size will be a problem for you. My “C” auto-completion file is almost 3.5 Megabytes and works very well. Currently it includes 3230 UEFI function definitions extracted from .h files and 463 keywords! Obviously I didn’t do this by hand; I wrote an AWK script that I use to generate a new (updated) auto-completion file periodically.

Keep in mind that you have to keep the entries sorted alphabetically. If you get something out of order, then you may never see a portion of your entries (but you will not get any kind of error message).