Self adaption has +/- limits ..
So, if pressure regulation is too high for correction limits , a code will come up.
Same for vac leaks..

Your car has access to the other modules , so if a code 19 CE lamp comes up, you should go to pin # 8 with a led/sw and see what codes are stored there .. that will get you more specific info.
Not saying it is not the ECU, just possible to get code 19 CE with
bad injector, bad reg, vac leak, etc...
Dealer may be right , but BC you have owner access on that model, it would be easy enough to open the hood and see what the computer has stored on the diagnostics memory of the HFM-SFI module...
{Archieves-Led tool}

Replacing the ECU and finding that the problem is remedied can entail several drive/learning cycles [ which can take a week].. so , maybe they did that ??...many times CE lamp is thought to be fixed w/part change and sure enough, a week later..there she is again..