If you use a space, you always get no results even when you should have. It's very annoying only being able to search by the first word.

I might be able to improve it slightly here, but due to in-game restrictions you're not actually searching for the localized tech/item names, but rather the tech/item "key" (which doesn't contain spaces).
It's a bit low priority, though, and I have some other stuff I need to work on, but I'll probably look into it at a later time.

Can you substitute any spaces with that get typed with dashes? It looks like the keys match the localization except with dashes where spaces would be.

The solution would be to search for the user-side string.

Search for "Landmines". You get Landfill and Landmines when the search string is "land", but add an "m" for "landm" and there are no results.