Not sure what caresheet you found but chances are it's mine.
I never actually kept them (although i'd like to do at some point) but i do know quite a few people who did. They don't express a lot of behaviors typical for other ants (like they don't do ant trails at all, just tandem-running) and while they generally seem rather chill and sluggish they are fairly fast in their own way, quickly gathering around food items and chewing on them even if they are still half-frozen.
Soil or sand-clay-mix with a layer of leaf-litter on top makes a great substrate (if you want to keep them dry) but they can also be kept in a little miniature greenhouse.
You're right, it's yours! I just checked. I feel better about it now, I was worried about reliability when I didn't know if it was from good source or not.
I never thought about a little miniature greenhouse for keeping ants, that sounds nice! I was thinking about getting some kind of terrarium with acorns and stuff around for them to nest in, even if it means I don't get to see inside. Or at least placing a small nest inside the outer world, so they can move around more easily and explore.
Do you know where to get them in the EU? I might not be able to get them right away but it would be good to have an idea of things like what the best time for shipping etc. is. I know some people seem to just catch them in the wild, but I'd be afraid of accidentally getting some random other species I might not have the right setup for.
Also, do you know what the differences between the different temnothorax species are? It sounds like they engage in slightly different behaviours. I'm inclined towards nylanderi, but I should probably make sure first.
Thank you so much for being patient and answering my questions!