looking at this again you will need to rethink your events...
you need to give your healthbar a variable, or a global variable if you prefer, lets call it regen, then when regeneration is possible trigger:...
set "regen" to score
score => regen + 25... add 1 to health
Trigger once set "regen" to score
So every time your score is 25 over the last health top up it will add another and re start the "regen" counter...