They seem so much powerful compared to the other timeline
shareProbably not. They were afraid of Cell who if absorbing either of them made him stronger. We don't know if Buu could do that with them but it's possible.
Whether it's Fay, skinny or kid Buu he'd be too much for them
I agree, they wouldn't be able to take him on together. Remember, in the series Trunks, after his huge power up in the HBTC, went back and was able to take them down easily. This was the same Trunks that was killed effortlessly by cell in his perfect form. Buu was way stronger than anything the Z Fighters had ever faced, including Cell. So no, Future 17 and 18 would loose pretty badly to Buu.
*Edit: Also I'm pretty sure Trunks says in the series that Future 17 and 18 are not as strong as the 17 and 18 in the current timeline. I realize the thread is probably dead, but I like DBZ.