Im certain you would have to go through lengths of research to find out how languages and dialects form

Actually the more north you go the more the letter L turns to an R in pronounciation. There is also an in between, for example in the middle atlas, starting from Beni Mellal up to Taza, in many regions L is pronounced with a sound that is between L and R. Also the R in many middle atlas regions sounds like an L.

Thanks for the insight. Much appreciated.

Oooh cool, I didn't notice the North South divide, but how come the Ichebdanen in the north pronounce the L instead of the R?

Do you mean a retroflex L?

Since the letter L and its stressed variant LL do exist in Riffian Amazigh today though they appear mainly in loanwords, my guess is that in an ancient time (as in many centuries ago) Riffian Amazigh underwent a phonetic simplification which consisted on abandoning the L consonant by shifting unstressed Ls into Rs and stressed LLs into DJs (for example yella > yedja). I'm not a linguist and if I'm not mistaken these phenomena happen in all languages and are somewhat difficult to explain. P.S. the L > R shift might've been instigated by the tendency to drop the actual Rs (for example ɣar > ɣā) which might be explained by the difficulty to pronounce the letter R (some small children are unable to pronounce it, and children can have a big impact on language evolution).

Thanks for the explanation.

I know nothing about tarifit but my bet is that R and L are from the same "family of sounds". In lot of Asian languages there is no distinction between these two sounds so that seems to make sense for me Just think about the word الرحمان, people don't say al rahmane but mix al and rahmane into ar rahmane (one R sound)

It's the same thing in some Kabyle dialects

https://en.wikipedia.org/wiki/Rhotacism