I had to skip those spirits, because there was no weapon accessible able to harm them. Now I'm in month 14, have set up a couple of bases - for the lack of anything else to do with the sponsor money - and just had the first landed UFO.
For the last 5-6 months, I have no longer had nothing to research, except a random new monster type or a live alien now and then. Looking at the research tree, to get any real progress one would likely have to capture more live enemies to learn of runic weapons, runes, magic, etc. The problem is that there appear to be no means to do so except by accident or by taking big risks of melee combat. Tazer appears to be a useless weapon so you're essentially out of options. Lore-wise requiring capturing more live enemies and interrogating them makes sense (also like in TWoTS) but I wonder if the means how to do so is balanced. The only thing I'm wondering are smoke grenades as an "attack weapon", because it appears to stun the soldiers in one turn, but the enemies don't appear to stay in it long enough or it's not otherwise effective. So, as it is, you just get a random stunning with regular weapons or a surrender now and then. And that doesn't seem to be enough to steadily progress the research tree with only ~50 researchers. EDIT: I had missed dart rifle and tranquilizer darts; those seem to be useful at least against goblins.
Another really strange feature is "melee-range dodging" - there is very little point why it is better to fire your weapons from 1 square away rather than from an adjacent square. I can't understand why you need to run 1 square away before counter-attacking, if an enemy comes next to you (and attacks you first). This makes me even wonder if there is some bug in this feature.