Player rating for tournaments across all installments of Heroes.

I completely disagree! Bonuses are not needed at all!
Instead of rating bonuses, we can give Grail bonuses.
That is, using the formulas of AlexeyPank, give a bonus not to the rating, but to the Grails.
In this way, we will maintain interest in achieving the maximum rating and eliminate unnecessary additions from the rating that do not reflect the player's actual skill.