Hi. Was on a JAL flight which was cancelled (pre-Haneda incident) due to a mechanical issue in December

We were rebooked on another airline the following day.

I saw in another forum that JAL could / would compensate costs for a hotel room and a potential missed day in Japan.

Seems like that might be accurate per :
https://www.jal.co.jp/jp/en/inter/change/expenses/

Would anyone know how/where to submit expenses via a web forum or email?