"Florescent" is a word, but it's a completely different word from "fluorescent". It's related to "flourish", not "fluorite". (Firefox is not marking any words in this paragraph as misspelled.)

And, yes, "English" and "French" should be capitalized when referring to the countries and/or languages. For counter-example, there is a verb "to french" that refers to trimming into thin strips in a culinary context, thus the "french fry". (Notably, Firefox wants me to capitalize those instances.)