"Been" is not necessary. (It could be used, but would change the meaning slightly.) The apostrophe S is a contraction of "is," so "taken" can be interpreted as either a passive participle or as an adjective -- in the present tense. Note that in American English, contractions are written after pronouns, but not after proper or common nouns. In the spoken language, the contractions are indeed used, however.

If we rewrite the key part spelling out the verb, we have these. 1. (without "been") ... everyone's situation IS taken account of. 2. (with "been") ... everyone's situation HAS BEEN taken account of. I would say both are good sentences. The former is referring to the state (the matter is settled), while the latter expresses the outcome of a recent action(the matter has just been taken care of). So they state the same idea but differ in the way of presenting it. A simpler pair of sentences might illustrate the point better. Both these sentences are correct. - The concert is canceled - emphasizes the canceled state. - The concert has been canceled - describes a recent action.

"I do feel everyone's particular situation's HAS BEEN taken CARE of, so we all feel it's tailor-made for us." Or: "I do feel everyone's particular situation's HAS BEEN taken INTO ACCOUNT, so we all feel it's tailor-made for us."

I think this is a better way to construct this sentence. . . " I do feel everyone's particular situation should be taken account of, so we all feel as if, it's tailor made for us".