Firstly, at the time of this posting, you have Viper at level 85. You don't have everything unlocked, so you're not really in a position to talk about how anything plays at the moment. Nobody here will take you seriously until and unless you show you understand how the job plays once you have all the skills unlocked and hotbarred properly.
I'm also using an XBox controller, and multiple players with physical disabilities who are forced to play ONLY with controller have outright come out and said you're 100% wrong on literally everything you've written. Twinfang and Twinblood should
absolutely not be consolidated into Serpent's Tail, because that ruins the "wax-on, wax-off" rhythm and flow of the job when you hotbar it
properly. You clearly don't understand the rhythm and flow of double-weaving oGCDs.
Viper is EXTREMELY comfortable to play on controller and the button ergonomics are totally fine. But oh look, yet another
healer main coming in to try and dumb down melee DPS jobs on the altar of "accessibility" none of the melee DPS mains asked for, or want, physically-handicapped players included.
Everything you wrote is legitimately a problem of your own misunderstanding of the role. It's clear this is an issue either of your own ineptitude, and/or lack of skill with oGCD double-weaving (which melee DPS mains
enjoy, but healer mains historically struggle with), not with the job itself. I expect nothing less though of a healer main trying to jump into melee DPS. Leave it to the most passive of players to complain that the most aggressive of jobs are too much for them to handle, and argue to ruin everyone else's fun for something they're not going to spend more than 5 minutes with anyway after they get what they want. It's not like we haven't dealt with this for the past 7 years, so your hot take is rather old-hat at this point.
Here are my hotbars. I'm willing to bet you don't even have the W-Cross Hotbar enabled like this.
Now go away and stop trying to ruin everyone else's fun to play control freak on the internet. Nobody wants you here.