It's funny how worked up and self righteous one could get even while recognizing that they don't actually understand the concept. It's particularly amusing that you were alarmed by "front" (what, like a mafia front?) when there's also a "back".
I have never worked at Citi but I can make reasonable guesses as to what these accounts are.
Wash is a term that means "funds did not leave the firm" (you may have heard the expression "it's a wash" to mean "things net out to 0."
Front and back may have to do with direction of funds flow, or perhaps a hierarchy of accounts (like "we are pulling from account X on the back-end and into account Y on the front-end")
Not saying these are exactly right, point is that as someone who's been in finance for a long time these are totally innocent.
Honestly with names like "front" and "wash" the whole thing should be checked by tax officials. The words probably mean something else, but ... wow