Markings
You can add up to 20 marking scenes per video.
You can add multiple items per marking scene.
The marking scene duration can be set between 1-10 seconds.
Subtitles
You can add up to 99 subtitle tracks per video.
The character limit for a subtitle track is 50 full-width or 100 half-width characters.
Related:
▼Add captions, symbols, or frames to video (Web Browser)
https://teachme.jp/8/manuals/14366698/
▼Add subtitles to your video (Web Browser)
https://teachme.jp/8/manuals/15272626/