Oh, it's not really incompetence. Don't be so hard on yourself.
It can be difficult to describe the precision of a regex in a few words that fit on a menu item. And there are often subtle variations that have to be accounted for.
For Text Toolbox, which implements common text conversions with regexes, I resorted to short menu "topics" essentially that expanded into prompts for options where necessary with some explanatory text.
Text manipulation is complex. Describing it (in words, alas) is difficult. Keep fighting the good fight!