Both Fate/Grand Order and Touhou Project have a significantly higher number of female characters than male characters, with specific design and market reasons behind these ratios.
"Waifus" tend to sell better in the gacha game market, and gender-bending is a common thing (this practice originated from the original Fate/Stay Night concept, where a female protagonist summoning a male King Arthur was changed to a male protagonist and a female King Arthur for better marketability).
There are often in-universe justifications for these gender-swaps, such as a character taking on an ideal form of beauty (like Da Vinci using the Mona Lisa's form) or originating from a parallel universe.
Many female characters have numerous alternate versions (e.g., summer, holiday events) that are new playable characters, further inflating the female count compared to male characters, who less frequently receive new versions.
ZUN initially felt female characters were simply easier to draw (citing less angular jawlines, lack of facial hair, and more expressive eyes). A quote from him:
"In terms of why there are more girls in the series than men, that's definitely a conscious design decision that I made. I believe that the play style of danmaku games has a feminine aspect to it. It's not a toe-to-toe contest of strength; you don't simply run up and pummel the enemy. With danmaku, I'm trying to make games that are beautiful. The way the bullets move, the way the game is played, it's a visual spectacle, and I think it has beauty in it. When you think of beauty as a general thing, you tend to think of women rather than men, so it's more a case of... I think danmaku and the games I create are more about aesthetics than they are about action. Although they feature bullets, they're not about guns. Something that I think maybe people assume, is that I put a lot of girls in because it's what my fans want, but that's not the case. That has nothing to do with it. I think that putting in characters absolutely has an effect on the gameplay and on the game's design. They're not arbitrary at all, they're part of the design of the game."
To summarize, according to ZUN, the creator of the Touhou Project, the predominance of female characters is a conscious design decision based on his view that danmaku gameplay has a feminine aspect focused on aesthetic beauty rather than strength. He states that this choice is integral to the game's design and artistic philosophy, not a response to fan demand.