I have never said "Chimera" which the ch sound. Nor have I really heard it used that way.
I've only heard idiots and the ignorant say "melee" with an "EE" sound. I don't think those are good examples of Americanization.
My last name, however, is. In German the pronounciation is something like "uhr-lurs." However, we say it "EE-lers."
However, Chimera's statement still doesn't look like a linguist's post because it completely ignores what happens in most shortenings of words (at least in English). Often the first sound of a following syllable is adopted by first syllable. Since the new name is no longer developing in the old language, it develops in the new language. Thus it would not be incorrect, nor unusual to see a consonant combination adopt a more common sound. Thus "chim-chim" (said like the monkey's name) wouldn't be an odd shortage at all. Though I still think something pronounced "Kim" would be more common.
further, "Faux Pas" may be a French word in origin, but English likes to hijack words. phrases like "faux pas" and "hors d'oeurve" are so commonly used in English that they are now considered English (being the descriptivist language it is). You can feel free to italicize it to feel more multi-lingual, but it is hardly necessary to do so.
Or do we need to italicize words like "alliance" and "maize" too?