Penipeni is on the front, not on the bottom, so it wouldn't be affected. Anyaru is usually on the front too, but it could be on the bottom. Mamumamu is weird. Diagrams and such, usually show it to be on the front, or make it the same organ as penipeni. Yet, yukkuri are often doing it doggy-style or present their rears to their sex partners.
Anyways, the answer is no. But a crippled yukkuri won't have much chance to use them anyway.
(Some date) I went to a yukkuri nest and lured out the baby yukkuris with sweets, and brought them home. The parent yukkuri was out foraging so this was an easy task. First baby Reimu's feet were burned with an alcohol lamp. She twisted her body and flapped her braids (sideburns) but she could not resist me, and so she was abusively burnt. Her sisters in the aquarium shook. What a good expression on their faces.
bottom. "___ the __th" (calendar date) "I lured some baby yukkuri out of their yukkuri nest with some pastries and took them home. Doing this while the parent yukkuri were out foraging was easy. In any case, I slowly and deliberately roasted one of the baby Reimus' foot over an alcohol burner. Aside from twisting its body around and waggling its sidelocks, it's powerless to resist. Man, I wanna to bully them so much. Her sisters are wobbling about noisily inside the fish tank. What nice expressions they have on."
>>Doing this while the parent yukkuri were out foraging was easy.
Given how it's shown to be relatively easy to take care of adult Reimus and Marisas, I find this line to be a little more humorous than it should be. As far as abuse/violence goes, I'd like for Kiri to pick on some adults (or the whole family) sometime down the road.