Glossary, earlier translations and suggestions
Glossary
A project can keep a glossary per language: terms with their agreed translation and a note, and names that are never translated, like the product's own name. Terms in the English are underlined in the editor and listed on the right. If your translation leaves out a name that should stay as it is, or uses another word for a glossary term, you see a warning.
The glossary comes from the project's repository, from TBX files such as glossary/de.tbx, and is read again on every push that changes them.
Earlier translations
"Seen before" lists translations of the same English, and of similar English, from this project and other public projects. The percentage says how close the English is. Click one, or press Alt and its number, to start from it.
Suggestions
If you can't save translations in a project, you can suggest them. Anyone who can translate there sees your suggestion next to the string and can use it with one click.
Babblebird also leaves a suggestion when the same translation was changed in Babblebird and in the repository at the same time: the repository's version wins, and the one made here waits as a suggestion marked "changed in the repository meanwhile", so nobody's work is lost.