This page has some guidelines for making translations for Thrive.
No machine translations
If you do not speak a language, do not translate it or vote on suggestions. Don't use machine translations (Google Translate etc.) unless you are familiar with the target language and can rewrite the translation to be correct and idiomatic in the target language.
Some text in the game use bbcode "[tag]content[/tag]" in them. Normal bbcode tags like bold ("[b]") etc. can have their content translated normally. Thrive special bbcode tags that look up information from the game configuration json must not be translated. For example references to a compound like "[thrive:compound]glucose[/thrive:glucose]" may not be translated. That text must be kept as-is in any translations.
Reconstructing made-up words
Many words used in Thrive aren't real words. Instead they have been constructed specifically for use in Thrive. These should be attempted to be translated in the same way they are formed for English.
For example the word "Chemoplast" is made up of the parts "chemo" and "plast", which can be separately translated. For example a possible Finnish translation would be "kemo" and "plasti" to form "kemoplasti". This way translations can be done to reconstruct what the word could look like if Thrive was developed in the target language. Some terms can be left as-is if no good reconstruction can be done.
What should also be kept in mind is the pattern that organelles follow in the target language. The reconstructed organelle names should be made to conform to the patterns that real organelle names follow in the target language. This will also apply to words made up for later stages.
Some more examples were mentioned on the forums.
No broken translation
Please don't submit broken translations (other than as suggestions) on the translation site as if those end up in the game (someone doesn't remove it), then the game might be unplayable in the language you are translating. It is always better to let the default English text be used rather than an inadequate translation.
Some of the automated checks on the translation website can be false positives. As such they can be dismissed if the translation is correct and styling is good for the target language.
Key name translations
If you look to the right-hand side there is an info panel about each piece of text. If the source location contains "key_mapping/KeyNames.cs" then it means that, that translation is for a key name. Keys should be translated as a commonly accepted name for them in the translated language. If there isn't one used then whatever is usually printed in keyboards in that country should be used, this often seems to match what the English name for the key is.
Due to the way Godot passes us the name, some key names are pretty simple like "HOME", but might conflict with other translations. If such cases are found we'll handle this by differentiating the key and the other word translation.
Merging from Weblate
This is a note for developers: translation commits need to be merged normally otherwise weblate will not be happy and will keep complaining about conflicts.