Games between players of a different country should have twice the weighting of a game between two players from the same country. And near(female)-near(female) games should also be weighted to a half (so that a near(female)-near(female) game between players of the same country would be a quarter of the rating of a non near(female)-near(female) game between two players from a different country).
TLDR Double the weighting of games between players from different countries except those that are near-(female)-near-(female), keeping those and pairings between players from the same country the same, except the pairings from the same country that are near(female)-near(female).
The reason is that near(female)-near(female) games are not common in open tournaments, and giving them half the weighting is more than made up by games from female-only tournaments--which should exist as much as open tournaments but with half the weight so as not to skew the ratings, for example at the end of the recent years of the Women's Korean Baduk League, Choi Jeong 9p seems to have the Iyama Yuta 9p in Japan effect.
I tried e-mailing Rémi Coulom but I'm not sure if I ever got his email right, so I post this on this forum!
In the the WHR rating system I plan to make I intend to use more advanced system that tracks how many times you've played an opponent in the (time) vicinity of that rating point and reduces the weighting accordingly, but I think the simpler method I outlined here more than good enough, not even a need to do it by tournament but just by player flag.
Goods luck to you both!