You're not kidding about info being hard to find.
This is likely of no damn use to you...but just in case:
There's stuff being sold that purports to combine citronella with heat release pad...ie it's a lantern where a small candle sits beneath the pad and warms the pad which is imbued with citronella.
It's alleged not to be smoky.....
It's sold here for outdoor use...like on outdoor dinner tables...and, like most citronella, doesn't do very much out doors (I have friends who have tried it) but I do wonder if, unless you find a pad that is safe for all of you, if it might not be worth a try on your balcony....(is that where the bastards are coming from? I assume your other windows are meshed?)
I have a problem of them coming inside because I leave the screen door to my balcony open a tad for Miranda. You can get automatic low level pyrethrum sprayers that come on at dusk to zap the little buggers that lurk on the balcony.
I just pyrethrum spray the balcony by hand every few days (but my balcony is quite enclosed) and zap the bedroom with pyrethrum if they are about (you may not want to do this.)
If you get a little burner designed for diffusing aromatic oils (you know the ones where a little bowl of water sits above a tea candle) you can put citronella in that, and it will diffuse the citronella without smoke.
I found one citronella heating pad being sold online, but it was from China, and frankly, with their quality control I wouldn't dream of buying it.
Closing my balcony doors from dusk until it is really dark limits the number of mozzies that try to come in.
Anyhoo, sorry I can't be of help re what you want...but this may bump the thread at least.