General

On a Cannoneer?

That seems a little low.

My cannoneer hits 21k without dice roll at lvl 112
Running with All link skills lvl 1 (Except Jett and AB at 0)
~20% str
maybe 200 atk total?

Try to get some cheap 6% earrings and 3% gear if you don't already have

And link skills + Char card set helps more than you think!
I start every character with 3k HP and 35 atk just from Card set + Cygnus blessing!

You dont really have to worry about your range until you can get proper equips lvl 140+ equips

Then focus on obtaining % equips when your a decent enough level.

Who the hell cares what your range is at 123?
Just get to 180 or whatever level you need to be to get your skills all maxed before you start caring about that