This is correct. Rs and Ls are linguistically the same letter.
Think about Asians who can only say one or the other.
Especially with ancient languages, you should try interchanging them and see what it looks like.
It can be enlightening.
Probably, but it's pretty standard linguistics theory that lots of languages don't differentiate L and R, so if you see an L, you can replace it with an R and see if it makes more sense to you or matches up with something written in another language.
The ancient world is a multi-lingual environment, and you have to keep in mind that the same word rendered in a different alphabet or language, may look different.
There's all the Grimm's Law and other theories of sound shift you can learn too.
It's more fluid than that, really, but you can assume in any language that a T and a D might be interchangeable. Th may or may not exist. And a C, K, or H, might be the same sound. Geneaologists run into this with immigrants who change their names over time.
Historians need to be always aware of it. Clovis=Louis=Ludwig=Choldwig, etc.
Salman=Suleiman=Solomon=Schlomo, etc.
Oh, and don't forget that the Semitic language alphabets and some others don't use vowels, so only the consonants really matter.
Thanks. This is an interesting source.
I've seen other pieces about the similarities between Irish and Berber languages, but this one is new to me.