You dont need to change anything in the ECU software. I've done the conversion myself with no issues. If youve got smoke at warmup you might want to tweak warmup enrichment via KFFWL

You do need to change stuff in non return to return conversion because injector pressure is calculated different on those, as said look at rkti module and such.

I apologize for the spelling mistakes, I don't know English very well. After mounting the return system, lambda up to 3000 rpm, I see a very rich mixture (over 1.1), this with a 3 bar regulator and at a very high speed, it remains poor and cuts the acceleration. Sometimes, at idle it emits a lot of smoke and the lambda is very high at that moment. I will study the problem in the previous discussions in order to understand exactly what it is about, until then I will mount the returnless system because it is a daily car. I apologize if I bothered anyone

That's a LEAN mixture. If you're asking for power at that lambda the ECU will definitely cut the power to save the engine.