I think it would depend on where exactly they are located. If they are more on the bone and not close to the tendons or joints, they probably won't cause issues. Based on my understanding, splints are usually only cosmetic once they're "healed".
Indie had a splint on each front leg, both were caused by trauma. One was more forward and a bit closer to her knee, and the other was slightly lower and farther back. I would talk to a vet or take pictures of them to post on here. Indie's were of a decent size but in the month and a half I had her, they never bothered her.
Forever loved, never forgotten; my beautiful Indie. <3 Hoofprints on my heart.