sound, thanks for your very helpful answer.
I hope FSRS7 will solve my problem, because expertium wrote in another thread that it will handle same day reviews properly. Add non-linear grade-delta-difficulty
Looking at the formulas of FSRS6, I don’t see how it could adapt to the case where a user finds the card very difficult on the first day of learning, but can then mostly recall it from long-term memory much easier.