That's a shame, many video players have the function of changing playing speed.
For some spells I used algorithms like playing animation from beginning to end and then from end to beginning. If renpy doesn't support this either, more complex gifs will be needed for such cases.
Hmm lots of work again in RL could you tell me whats needed for a pack ( the minimum as action/clothing/expression ) that way ill focus on those first and make 1
Besides sex scenes, profile pictures with various emotions, backgrounds and clothes are needed.
At very least angry, indifferent, sad and happy are needed for a pack. Most big packs usually have angry, confident, indifferent, happy, sad, scared, shy, suggestive, tired and uncertain profile pic too.
Everyday clothes are default ones, most characters have them, except random ones. For random characters you can pick them freely as long as they are not too formal or revealing. Formal is an elegant dress of some kind, revealing shows more skin than usual one. For beach a swimsuit or bikini of any kind will be useful.
For rest scenes either indoor clothes or lingerie will be useful.
Other clothes are quite optional.
The most useful backgrounds are white or any other light color (multipurpose), general indoors (inside a generic building), living indoors (living room), beach, general outdoors (usually just blue sky as background), dungeon (especially for rape scenes).
You don't have to make all possible combinations for sex pics, they could have two types: with white bg and with living room. These are the most common cases after all. And of course you don't have to do all emotions for sex too, we need normal ones (ecstatic) and rape ones (sad). There could be any clothes, but for the sake of variety different clothes for different sex scenes are welcomed (like revealing/nude/lingerie).
You could try to make a pack how you see it suitable, and then I'll tell you what should be added to make it better. It's kinda difficult to describe it from the scratch, since I never did it before, instead making packs from already existing pics