I can't see having to unbolt the transmission to do this R&R.
I just helped a guy replace the oil filter housing adapter on his Golf 2.5, that's why I posted the video I found and included the intake manifold removal video to fill in the missing info.
We did entire job was done in under 2 hours, .... yes my familiarity removing the intake manifold helps a lot, as does having the proper tool to unbolt the intake manifold. The fuel hose and the electrical harmess connections get disconnected but injectors, throttle body and sensors stay put on the intake manifold.
I;ll upload some pics of the key tools i use to quickly loosen the bolts on the intake manifold as I feel this is where many guys get stuck. The same tools are used to torque the intake manifold bolts to 9 nm
I didn't have the torque spec for the oil filter housing adaper bolts, so I torqued the bolts to 25 ft lbs, should be close enough