Such threads have been answered several times. Raids are being done by CMs or me whenever we have time to do it. Some raids will be done at "normal" hours, some not, as always.
Also those "15" players playing at late hours matter as much as you, they deserve to enjoy some raids too.
And inbefore you say "all raids" are done late...
lastest manual raids and their hours:
Manaphy: 23:20 ~
Mega Scizor: 18:50 ~
Magma Golem: 22:30~
Mewtwo: 3:00~
Mew: 18:05 ~
Donald Trump: 19:05~
Lady Gardevoir: 18:15~
Dialga: 17:30 ~
Dakrai: 1:30~
Xerneas 22:30~
Groudon: 20:30~
Kyogre: 17:45~
Hoopa: 02:00~
If most of the raids are being done in european hours and you are complaining for 1 celebi being late, then you have problem with selfishness. Enjoy those, that you can attend and let others enjoy those, that are being done later.