And here's the response support gave me :
Thank you for contacting GREE Support.
I apologize for any confusion which may have been experienced during our current event.
The temporary boosts acquired during the WD Jamaica event are not visible on the Profile page. For technical reasons, this type of boost cannot be included with the permanent boosts. Please be assured that the boosts are being applied while during the event.
Certain types of boost, generally those that make something smaller, fewer or shorter(i.e. "fewer casualties", "shorter upgrade times", "less time till your health refills") have diminishing returns when there are multiple sources of that boost on your account or faction. What that means is, each new source of that boost that you add is slightly less effective. So for instance if you have a 5% health regen boost effect and then another 5% health regen boost is added, you would see a total boost effect of 9%.
This is intentional, because these boosts cannot logically go below zero. It's impossible to have faster-than-instant upgrade times, for instance. Or to have a casualty rate modifier so low that you actually get units back. So for these boost types, we have the diminishing returns effect stated as above. New sources of the boost will still add to your total and progress you, though.
Here's an example of how health regeneration boosts are calculated:
If a player has two 5% multiplicative bonuses and two 15% multiplicative bonuses of the same type, instead of having a combined 40% bonus, he would have a combined 34% bonus (.95*.95*.85*.85) = .652, which, when subtracted from 1, is .348, or a .34 (34%) bonus. Compare this with two additive bonuses of 5% and two additive bonuses of 15%, which would look like 1 + .05 + .05 + .15 + .15 or 1.4, or a combined 40% total bonus.
Although the examples given above reference the faction boosts, this also applies to personal boosts from units or buildings that display on the profile.
Health regeneration without boosts for these event types is as follows:
Epic Boss - 25 minutes
Raid Boss - 100 minutes
World Domination - 60 minutes
Please let me know if you have any further questions about health regeneration boosts!