Okay. The official spelling is Llyr. L-L-Y-R. It's even on the CG's that I extracted from the original game. How in God's name does one explain the pronunciation of "Suirru"? I mean, it defies even the Japanese confusion of L's and R's! I would understand "Rirru", but "Suirru"? Somebody help me out here, please. >_<
As per Tenka Seiha apparently it's the Welsh "ll". Japanese Wikipedia on her shows "名前の由来は海神・シール（Llyr) " literally "The Name's Origin is from the see god Sheer (Llyr)".