>>51210805with the EN hologra the EN members themselves most likely had a little bit more of a hand in writing their lines; I deduce this from the fact that almost no one in the company in charge of hologra other than A-chan really speaks actual english and even she doesn't fully - it makes sense to think they gave them a rough idea of the scenario and asked them to come up with lines since they knew the EN members would be better at it than them.
Therefore this one line probably came from Mumei herself i.e. it's just as you thought, she's fucking /here/ and it is in fact a tokoyami tower reference. Mumei is one of the few members other than Mori that has actual evidence suggesting she may be /here/ that is pretty hard to argue against so that is the most likely explanation.