Yes, it looks like Schefflera arbicola, (variegated?) A glacially slow growing plant from what I've seen. Do you have a spot with more light?

Generally, it can be trimmed with the expectation of new foliage growing at a lower level. When the plant is growing most vigorously is the best time to do that. It can be hard to tell when a slow plant is vigorous, but that's generally during summer. As far north as you are, I'd definitely wait a couple months to do it during the longest days of the year, probably in conjunction with a repot.

Another option to make the pot look more full would be to add a shorter companion that likes the same amount of light and moisture.

FWIW, it's best to have one person caring for the plants (as long as that person has the time to do it.)

this photo was taken in the very late afternoon, it's actually much, much brighter there.

so if i wait a bit longer and cut off the antennae, it should regrow from the bottom? it won't just up and die off? tho i suppose that would always be a risk.

TIA

Yeah, if only we had a crystal ball...! It 'should' produce new growth from the tip of what is left of the trunk after you cut, though new growth could come from lower on the trunk.

Are the 2 trunks connected at the bottom? If so, I would cut them off at diff times, so you're not removing the plants' entire ability to produce food (through photosynthesis in the leaves.) After you see growth from cutting the first, then do the 2nd.