My question: Is it possible to add links to the customized text? Also is it possible for this text with links to be translated like other text on the page?
Reading through your post, I wanted to provide some more information, as it can help others as well.
You should be able to add a link to the signup page on the organization-selection screen, using page templates firstly, for which more details can be found in our documentation here.
Additionally, you will need to write some HTML text that fits your use-case. I recommend checking out this following Community Post for some code examples that should help.
Regarding the translation, it should be possible to adapt the custom text when writing the HTML using the locale variable, as depicted here.