T5 is the first brick wall to come up against in coil now. It is much easier now with the buff and everyone in i90+ gear but it is still easy to mess up. One of the first fights where 8 people have to pay attention to mechanics or the group fails. It takes practice and patience even with the echo buff and gear for most people the first time in there. None of the mechanics are inherently that difficult but you just can't forget about them or ignore them (well DS and conflags you can to a degree now).

If you are struggling, take a deep breath and enjoy the challenge the game is finally presenting to you. There is no need to get past T5 unless you enjoy doing progressively harder content. So if you don't like getting together with 8 other people to work on content that takes time to learn, don't worry about T5. It's a good gate to get party's ready for SCOB.