so. HOW did cap get back to the primary timeline WITHOUT being on the landing pad?
i'll skip your answer because i already know where it's going. the movie states that you rejoin the proper timeline back through the doorway you left it. like ant-man coming back in the van. even though the van moved, that was his link. the time heist crew all returned to the same spot, even though they took different amounts of time (including evil-nebula and war machine. they were on the same mission but returned at different times, but still showed up with the rest of everyone at the same time) though, rhodey DOES have the line about "syncing up with the others" so it's possible that you can choose to show up WHENEVER. however, the WHERE never changed. always on the landing pad.
the pad that hulk used to send cap back was a portable device. it's fair to say they packed it up and unloaded it for the nice scenery, i guess because it only serves to have cap sitting on a bench 30 feet away. so if cap used to temporal compass to return back his original timeline, he STILL would have shown up on the landing pad, not the bench. okay fine, he used the temporal compass to show up at a DIFFERENT time in order to have a nice entrance. he STILL WOULD HAVE SHOWN UP on the landing pad, wherever it was. probably in stark's/banner's lab. you know, when they were building the thing. right? how wouldn't they notice?
okay fine, cap, even as an old man, is still probably pretty lithe and nimble and could sneak out without anyone noticing. but i GUARANTEE you that someone, somewhere would notice the power surge and be like, wtf? but since NONE of that was actually shown or even hinted at, we are just filling in the blanks for a plothole so that it makes sense.
here's how it makes sense. the writers were told to have cap hand off the shield to falcon, just like they were told to have a female empowerment scene and so they just did it without caring about how consistent it is.