Plex is already searching for titles in the library language and original titles.
Adding “all languages” for each title will be quite an explosion – as you pointed out, the impact on storage might be manageable (while certainly bigger than you expect it to be)… however that’ll also mean that your server needs to deal with a multitude of the current number of records in its database (which will have an impact on the server performance).
Would you mind sharing the use case where you’re searching titles based on different translations? That might be helpful for others to decide if they want to vote for this suggestion.
There’s an existing suggestion asking to include metadata for additional languages for sharing with international users (so they can see and probably also search your media in their respective preferred language).
