掲示板 Forums - Hiragana Schedule.

Not sure. You can try resetting the schedule (you will lose all mastery for those terms) and then starting at a higher mastery by setting it manually for each term.

Basically, you'd reset master to 0 (unknown), set it to level 5 or 6 for all of the terms and theoretically it should work as if you'd just normally hit those levels and the default spacing should kick in.

Or just set the mastery manually without resetting the schedule, idk.

Honestly, I don't understand the system well enough and don't have access to your logs/user data, so you might just have to ask Michael directly. He probably won't get back to you for a long time though (given his situation).

Or just give up on mastery for Hiragana and review it every now and then