Note that you’ll have to choose which audio track(s) to include, as well as subtitles if you include them, for it to be BR compatible, which will also save on space. Just uncheck the ones you don’t want before you hit the button to let tsmuxer do its thing.

I may be misremembering about the number of audio tracks allowed and the number included in the MKV might be fine for a BR, but either way, you can uncheck (for example) all the foreign language ones you won’t need, or keep only the 5.1 or 2.0 DTS track if you think won’t switch between them. The DTS tracks especially eat up a good chunk of file size.

Pretty sure subtitles are limited to 32 tracks on a BR, though.