Can I use an acid other than sulfuric for hydrogen peroxide determination?
Don't use the organics!

This will severely mess up your titration because both permanganates as well as H2O2 will oxidize the carboxylic acids into explosive or corrosive things like peroxyacids (-C(O)OOH). Carboxylic acids are also usually weak, and the peroxy versions can be up to 1000 times weaker.

On the bright side, HCl is a strong acid, and you shouldn't have to worry about the production of chlorine gas; the only chlorine product should be MnCl2. However, since so much O2 Is being produced, your MnCl2 might contain a small amount chlorate impurities, so be wary of that if you plan to use the manganese chloride in the future.