Taking data on the gender ratio of collabs, comparing JP to EN
* Data taken between January 1, and March 20th at 5:00pm JST

~ JP data ~
Salome: 5-0, 5-0, 4-0, 2-0, 2-0
Hoshikawa: 4-0, 2-0, 2-0, 4-2, 4-4, 2-2, 2-2, 1-1 
Lize: 2-0, 2-0, 2-0, 2-0, 2-0, 2-2 
Deron:  3-0, 3-0, 2-0, 2-0, 2-0, 2-0, 3-1, 3-1, 2-1, 5-6 
Sasaki: 6-0, 4-0, 4-0, 2-0, 2-0, 2-0, 4-4, 2-2, 4-5 
Ange: 2-0, 2-0, 2-1, 3-2, 2-2, 2-2, 1-1, 2-4, 1-2 
Ars: 4-0, 4-0, 3-0, 3-0, 3-0, 3-0, 2-0, 2-0, 2-0, 2-0, 2-0, 2-0 2-1, 4-4, 2-2, 2-2, 2-2, 2-2, 2-2, 2-2, 1-1 
Shiina: 5-0, 4-0, 4-0, 3-0, 2-0, 2-0, 2-0, 2-1, 8-5, 7-4, 3-2, 2-2, 2-2, 2-2, 2-2, 2-2, 1-1 
Chima: 4-0, 2-0, 2-0, 3-1, 1-1 
Himawari: 8-0, 6-0, 3-0, 5-1, 3-1, 3-1, 3-1, 3-1, 2-1, 5-5, 2-2, 2-2, 2-4 
Amamiya: 4-0, 3-0, 2-0, 8-1, 3-1, 3-1, 3-1, 3-2, 2-3, 3-7 
Furen: 4-0, 4-0, 3-1, 2-1, 1-1, 5-6, 1-3 
Elu: 4-0, 4-0, 4-0, 4-0, 2-0, 2-0, 3-1, 2-1, 7-3, 4-4, 2-2, 2-2, 2-2, 2-2, 2-2, 1-1 
Ratna: 4-0, 4-0, 3-0, 2-0, 5-5, 2-2, 2-3, 1-4, 1-4, 1-4, 1-4, 1-4 
Kana: 2-0, 4-1, 4-4, 1-1, 1-1, 1-1, 1-4 

=====================
%f = percent female partners, not including self
%m = percent male partners, not including self
N: = number of collabs
P: = total collab partners, not including self
=====================
Salome: 100%f 0%m, N:5 P:13
Hoshikawa: 54%f 46%m, N:8 P:24
Lize: 75%f 25%m, N:6 P:8
Deron: 65%f 35%m, N:10 P:26
Sasaki: 66%f 34%m, N:9 P:32
Ange: 36%f 64%m, N:9 P:22 
Ars: 63%f 37%m, N:21 P:48
Shiina: 61%f 39%m, N:17 P:59
Chima: 78%f 22%m, N:5 P:9
Himawari: 64%f 36%m, N:13 P:53
Amamiya: 60%f 40%m, N:10 P:40
Furen: 52%f 48%m, N:7 P:25
Elu: 61%f 39%m, N:16 P:51
Ratna: 25%f 75%m, N:12 P:40 
Kana: 37%f, 63%m. N:7 P:19 

Less than 5 collabs: Mito, Inui, Nui, Chigusa, Suo, Claire

>> Net stats
-----------------
Total collabs: 155
All-girls collabs: 68 (44%)
Male-majority collabs: 16 (10%)
50/50 collabs: 42 (27%)
female collab partners: 58%

comments
----------
- Ratna's overwatch tournament accounts for 1/3 of the male-majority collabs
- A few of the others are very close ratios like 5-6

***************************************************************
~ EN Data ~
{ } = minecraft streams
Enna: 3-0, 3-0, 2-0, 2-0, 4-1, 3-2, 4-2, 3-3, 1-1 
Elira: 2-0, 2-0, 4-1, 3-1, 4-2, 3-2, 3-3, 3-3, 2-2, 1-3, 3-4, 2-5, {3-5, 2-5, 2-7, 1-6, 2-4, 1-5, 4-7, 1-2, 3-3} 
Millie: 3-0, 4-1, 4-2, 4-3, 1-3 
Finana: 3-0, 2-0, 2-0, 2-0, 2-0, 2-1, 2-1, 3-3, 1-1, 3-4, 1-3, 1-3, 1-5, 4-11 
Rosemi: 2-0, {3-5, 1-2, 2-4, 4-7, 3-6, 2-1}
Maria: 4-0, 3-1, 4-2, 2-2, 3-3, 2-5, {2-7, 1-2, 3-6, 5-3, 4-7, 4-6, 2-4, 2-4, 3-5}
Reimu: 4-0, 4-0, 3-0, 3-0, 3-0, 2-0, 2-0, 3-1, 4-2, 2-1, 4-3, 2-2, 1-2, 1-3 
Klara: 4-2, 2-1, 2-1, 2-1, 1-3, {1-3, 2-2, 2-1, 3-5, 2-4}

=====================
%f = percent female partners, not including self
%m = percent male partners, not including self
N: = number of collabs
P: = total collab partners, not including self
=====================
Enna: 64%f 36%m, N:9 P:25
Elira: 30%f 70%m, N:21 P:100
Millie: 55%f 45%m, N:5 P:20
Finana: 32%f 68%m, N:14 P:47
Rosemi: 29%f 71%m, N:7 P:35
Maria: 30%f 70%m, N:15 P:82
Reimu: 63%f 37%m, N:14 P:38
Klara: 32%f 68%m, N:10 P:34

Less than 5 collabs: Scarle, Aia, Twisty
Not EN: Meloco, Kotoka

>> Net stats
-----------------
Total collabs: 95
All-girls collabs: 21 (22%)
Male-majority collabs: 37 (39%)
50/50 collabs: 12 (13%)
female collab partners: 37%

comments
----------
- Elira mostly spams male-heavy collabs
- Ethyria is the only girls group that consistently generates girl-collabs
- Extremely male-heavy collabs with ratios beyond 2/1 exist in EN


***********************
~ Conclusions ~
Almost half of JP collabs are girls-only, and a high number of others are split-collabs. Male-majority collabs are quite infrequent and super male-heavy collabs barely exist. The fact that so many split collabs exist probably indicates an intentional policy to split certain collabs evenly by gender.

EN lacks girl-collabs, and the ones they do have are usually 1v1 collabs, or wave-collabs. Larger female-only collabs do not exist, unless it's a collab with JP. There seems to be no attempt at splitting collabs along gender lines. Instead there is an excess of super-heavy male collabs with gender ratios beyond 2/1.