It can be safely assumed that there will be almost certainly problems with the correct pronunciation, so as not to say certain confusion might occur with the similar names, which you mentioned.
According to my information the common pronunciation of
Silviu is Zil-vee-OO (the OO as in Ute-OO-teh)
Whereas the Italian
Silvio as known, Zil-vee-o,
Silvia, Zil-vee-ah,
Silvius, Zil-vee-ooss