What's 'liquid air' supposed to be in BI? K2 Atmospheric condensers can output Nitrogen, Oxygen or Hydrogen. Maybe use Oxygen instead of liquid air for those 2?
Done.
That said, I don't think a lot of modders are concerned with 0.17 at this point, as it's not like 0.17 is even the littlest bit more 'stable' than 0.18, because, well, it's Factorio and 'experimental' is still very solid. I think most modders are just targeting 0.18 for the most part.
Factorio 0.18 is very stable unless there is a breaking change, which happens sometimes. Have a look at the downloads: 3548 (for 0.18.16) vs. 2994 (for 0.17.48). If other modders think they can ignore Factorio 0.17, they are free to do so. But if I can accommodate about 45% of my users by keeping the 0.17 branch up to date, then that's exactly what I'm gonna do.
Plus, this is just about compatibility with K2 anyway, so this is about K2 + BI which means 0.18 as well. Not sure if it's worth even exploring K1 + BI + 0.17.
About 45% of the downloads were for 0.17. K2 doesn't run on Factorio 0.17, but "Krastorio Legacy" does. I just changed some logic to the code of 0.17.49/0.18.17 so that it will run with both versions. This way, I need to maintain only one version and can reuse everything except changelog.txt and info.json. So it's not only about K2/Factorio 0.18!
I'll probably remove a lot of redundant code once Factorio 1.0 is out. Until then, the redundant code will make my life easier. :-)