I've read that charge terminating NiMH by temperature rise is
not good or proper, that it has to be done by voltage monitoring.
By the time the NiMH cells heat up, the damage has been done.

Based on what I learned at Microsoft Hardware, this is not true. "Hitting"
the NiMH cell "hard", to the point where it significantly heats the cell,
supposedly gives a deeper charge.

I've have NiMHs get quite warm -- even hot -- in chargers. If one such
occurrence ruined the cell, then most of my cells would be useless. None is.