Due gets confused -- it sometimes thinks "an historic" is wrong, and sometimes thinks "a historic" is wrong. Actually, both should be considered correct.
I said "Palestine is a historic important place" and it says it's wrong. I don't think either should be wrong (some who speak English say "an" before historic). The order of the adjectives is the same as the original sentence.
I don't know about the Arabic sentence, but "historic" and "important" are adjectives, while the "historically" in your sentence is an adverb modifying "important"..