So "walking the trigger" is different than Ramping? This is a technique used with electro guns in semi mode? is it possible to reach the 12.5 BPS rate in semi with certain guns?
Ramping covers several different standards then? It is a generic term for these hyper ROF's?
Ramping is just a term for guns that are set neither fully automatic nor semi-only. There have been a few different tournament ramping standards and most boards that do ramping can be configured to do all sorts of exotic ramp methods. The only real common parts of ramping are 1) a gun fires semi-automatic under a certain trigger speed and 2) above the set speed, the gun is allowed to fire more shots than trigger pulls.
Practiced users can definitely exceed 12.5BPS in semi-only mode; the NPPL rules specify 15BPS as a limit even though that league does not allow any ramping or burst fire. I believe that limit is there because it's a limit in the ASTM standard defining paintball guns (though only called out specifically for automatic/burst mode guns).