I agree with your concerns here. Unless there’s a separate established system that is the source for these abbreviations it does seem like it goes against iNat guidelines.
I would guess that the person adding them has good intentions but may be unaware of the guidelines and the implications of creating their own abbreviations this ways. You can see who made these changes using taxon history and then message them directly to see what they’re basing this on.
Maybe they’re adding these to make adding IDs easier for themselves. In that case, you might want to explain that they can already use abbreviated versions of common or scientific names. For example “mad wag” or “mot flavive” will bring up the Madagascar Wagtail at the top of the list.