>>1698860you tested those things still right?
because that could be why if you didn't test, in either way, friction at a housing cut or overtightened or missing a washer caliper
pretty strange to happen if you did that stuff right but hmm
does the lever have a return spring? Those help.
Also yeah. All road calipers/levers are basically compatible if you wanted to upgrade to dual pivots (or in the front atleast). I'd bide your time and try buy some shiny-era shimano 105/ultegra/da ones cheap. Or grey tricolour. It's a good upgrade.