When installing the new fuel fittings it is important to trim the end of the hose so you get a fresh surface for the barb to seat inside the hose and fresh rubber to compress under the clamp. I guess the barb is a slightly different shape on the new fittings. The hoses are plenty long.
I didn't do this when I installed mine. At the Dragon raid Randy, from Triumph, told me it was supposed to be done. It ddin't leak when I put them on so didn't worry. Yesterday I smelled gas by my bike. I pulled the side cover by my left knee. Checked the hoses and they were dry. I started it up and let it run for a bit and there was fuel dripping down the lower hose. I pulled the hoses trimmed about 20mm off each hose, re-installed the fittings and now all is well.
I talked to my Triumph mechanic and he hadn't heard anything from Triumph about trimming the hoses. So it might be worth checking
Funny - it was clearly indicated on my service bulletin to trim the hoses. They even go as far as specifically indicating how much to trim from each hose.
Sounds like my service guy doesn't read notices or missed one.
Exactly why I do my own wrenching. Nobody cares about your ride like you do.