The double L is of Welsh origin and is a subtle "cL" so an exaggerated way of saying it would be "cLewellyn. The second double L is L as in hello.
Sorry to resurrect this, I only just saw the responses to my post.
Indeed, there are lots of Greek words containing "ch" in Latin. They are, as you say, Greek words. They are not Latin words. You may just as well claim that the word "die Pizza" is German, or "le week-end" French, because those words appear in the respective dictionaries.
Please go ahead and have a look at this thing you call a dictionary. There is no "ch" digraph in Latin.
Thanks, you've enlightened us, lol.
So, I was right with Chiasso and Porchetta. In Italian the c deteriorated but the ch (before i and e) survived and is still like old Latin.
I had chosen " schola " on purpose, because, as far as I can tell, it is a loanword, with a Latin ending too, not perceived as being Greek anymore, with a different meaning even, just like "car" in Swiss German and French.
I don't think there are any trends especially. Command of language varies per person and day. Sometimes tiredness affects pronunciation.