We can render multiple subtitle tracks in different languages onto the same video, but you have to take into account screen space to accommodate all the different languages. The subtitles will cover a lot of the screen, especially if it's going to have more than 2 languages.

We typically recommend creating separate videos for each language that can then be loaded on a website based on which language the end user selects.

We can also put subtitles over existing subtitles. This involves covering the old subtitles with the black boxing of the new subtitles, as long as the client is okay with that style-wise.