RE: the ronto, I’ve always figured they weren’t indigenous to Tatooine, but rather that they were imported somewhere along the line. I suspect there was some legends stuff somewhere along the line that contradicts that idea, but as far as I know it’s a valid theory again.
I think that pretty much everything we saw/heard of on Tatooine except Tuskens, Jawas, Krayt Dragons and Womp Rats are supposed to be imported.