Why a Headliner alternative depends on what you are actually trying to fix
Headliner answers a question podcasters have had for a decade: how do you put audio in a feed that only rewards video? Audiograms and waveform clips are the answer, and posting them automatically is the second half of it.
None of that is editing. If your clip is too long, mumbles in the middle and was recorded in a room with a fridge in it, Headliner will package the problem rather than fix it. That is the gap Montaj fills.