I’ve had the same problem with HeliBoard learning garbage. I just changed my settings though, and I think it should help:

1. Open HeliBoard settings
2. Open Text correction settings
3. Scroll all the way to the bottom, and turn off “Add words to personal dictionary”

If you scroll all the way to the top again, you can manually manage the personal dictionary, including adding words you do want, and deleting any junk that was added by mistake, before switching that setting off.

You may have missed “also.” The comment does not suggest replacing the current list.

Worth noting, the existing list dies actually appear to cover both known working and known not working apps - apps that do not work have their names given in strikethrough.