Cross-platform: Untranslatable words

We have a bunch of technical terminology in our app, and while we should make an effort to tone it down, we also have a responsibility to have accurate translations of the words we use.

Many words, like Spaces, might not have direct translations and instead be approximate based on various criteria. We should set up a [Weblate Glossary](https://docs.weblate.org/en/latest/user/glossary.html) with all the Element/Matrix specific terminology to give translators the best chance at translating them.

**This issue exists to collect those words, and the languages that have particular difficulty translating them.**