OK so the question is whether the engine auxiliary components go in with the subframe or before or afterwards.
Almost invariably, the air filter housing, radiator, intercooler, and some electrical components are not part of the engine cradle/subframe when it goes into the vehicle. So they go in either before, or afterwards.
But whether they go in before or after ... will vary. One vehicle design may be done one way, another one done a different way.
Whatever facilitates the most straightforward assembly process, is the right way to do it.
A lot of the auxiliary components (various gizmos and gadgets mounted on the firewall, wiring harness, etc) are easiest to get access to before the engine is in the way ... so they go in first.
Some vehicle designs might not have enough clearance for the powertrain to go in if the radiator/intercooler is in place ... so the radiator might go in afterward. But in other designs, it might not matter ... so it's whatever is most convenient on the line. Or if it doesn't matter, perhaps someone just makes an arbitrary decision about which way to do it. Or they do it in a certain order because "that's how we've always done it". Sometimes, that's just how it is.
A lot of vehicle manufacturers at least partially design the vehicle around the assembly sequence, and they *always* assemble everything in the same order, "just because".