"Zai-rinf" is the official pronunciation of "Xyrinfe"... so that can go on the wiki, probably...?
There is a silent "e"...
However, it may have different pronunciations in other dialects, et cetera... Mia says "sir-inf", Luna just says "X-whatever"...
The origin of the name itself was based on "Serenth"... a name Charlie suggested to name the once-nameless galaxy in which Serenity Horton, heroine of Newerth, had lived...
Charlie gave Serenity her name, as far as I know... I think the last name came from Days of Our Lives, though...?