Yes, pay them. I don't know if Swiss fines can be enforced in France, but you could be stopped at the Swiss border or by Swiss police next time you visit. If you ever return by car you could end up with the nice surprise of having a wheel clamp attached to your car.

If you don't pay the fines within 30 days, then a judge will determine the fines and this will be even more expensive, because you'll have to pay administrative fees on top of the fines.