Thanks for playing!
Ts 5-7 are always successful.
They count as a tech skills you know (once you discover em of course). So if you know TS1 and TS5, you're rolling 2 dice.
The intention of tech skills is that you pick 1, roll, and see if it failed or not. There is no reverting to a different skill. (But play as you wish)
I try to think about it realistically. If you attempt to dodge and strike, but miss the attack, it'd be a little odd if your arrows just caught on fire.
Hope this helps! If you have any more questions feel free to ask! I'm on the discord all the time and usually respond quicker there if that helps. Link to it at hinokodo.com