[Suggestion] Improving the reward system in PS2

Except with the formula you provided, that scenario is actually impossible. I'll use an exaggerated/unlikely scenario to keep the math simple because I'm lazy:
certs_gained= (Your_BE_share/Total_BE)*Facility_cert_value*1.5
(I just changed the win_modifier to 1.5 because apparently it's constant)

Take a situation where there are 10 players who average 1k exp:
(1k/10k)*100[*1.5] = 10 to 15 certs for everyone if everyone is roughly equal.
Now imagine that same fight, but an 11th player joins and makes 10k exp all by themselves because they understand the game better (also let's say they increase the cert value by 10 because they made the population larger):
(1k/20k)*110[*1.5] = 5.5 to 8.25 certs for the average player
(10k/20k)*110[*1.5] = 55 to 82.5 certs for the single good player
or the opposite: if everyone is really good at the game except for the 11th player it would then look like:
(1k/101k)*110[*1.5] = 1.08 to 1.63 certs for the average player who was in with the wrong crowd

As a bonus: People already get mad about stuff like, say, shotguns. Imagine how mad they'd get if getting killed by a shotgun meant their contribution was paused and they could get potentially fewer certs while the "no skill shotgun cheese" got extra contribution for scoring a kill.

In a later post you added: "certs_gained= (Your_BE_share/Total_BE)*Facility_cert_value*Win_modifier*(Battle_time/Facility_capture_time)" and I'm not even going to get into how that would encourage people to let the point flip back and forth so the battle lasts as long as possible - especially for bio labs which have a high facility_cert_value but also the lowest facility_capture_time.

This can also create problems.
For example, when a fight's starting up between Mao Tech Plant and Mao Southeast Gate. It's entirely possible that the tech plant's team will have all its sunderers inside the tech plant's SOI and it won't be getting captured. Similarly, the gate's team can have all its sunderers inside the gate's SOI and it won't be getting captured. Even though there could easily be a 96v96 battle going on, neither facility would be considered contested.

Speaking of 96v96, let's consider the exact opposite: what if this scenario happens on Briggs or something, where the nearest contested base is... say... Regent Rock Garrison? That's more than 1000m away, so where would all those certs go?

Certs, exp, same thing. (Well, 1 exp is like a little baby cert that's 0.4% as big as a grown up, adult cert but y'know.) It still doesn't address if one team could receive a reward because of the other two teams fighting.