Jayne is a tradition spelling personally I don't regard it as being an unusual spelling, it's just a variant, lot's of names have a number of spellings all of which are normal. Jhaiyn on the other hand, hmmmm.
We tried to chose names that are pretty simple and spellings that are fairly phonetic, I didn't want my children to have to tell people how to pronounce their name or how to spell it. It gets so tedious always having to help people out.