I noticed that i can obtain rare resources from slag on a planet where such resource is absent. Can you please consider making restriction for slag reprocessing recipes to be avaible only on planets with this resource?

I know, I've been thinking about how best to address that.

Maybe surface conditions like for simple coal liquification on vulcanus?

yep, working on it.

Done. Not able to test it properly at the moment, let me know if it works for you.

Slag reprocessing recipes with holmium ore, lithium and tungsten ore are locked by crafting surface conditions (good). But, recipes themselves allow absent resources - I can get tungsten ore and holmium ore on Aquilo, though in my opinion this is ok and seems balanced and fair.

That was an oversight, I'll fix that in the next patch.

While thinking about that, should uranium ore from slag be limited to Nauvis?

Done. Not able to test it properly at the moment, let me know if it works for you.

Just wanted to mention that tungsten slag processing is now missing a locale key.

Thanks, fixed.