rge- I have just spent the last minute of my life saying Elowen and Rowan every way I can think of... yelling, really fast, slowly, etc. So now that my fiancé thinks I am INSANE, I will say that I don't think they would cause too much confusion. Other than you and your husband, how many people will say their names together?
I like it. I don't mind matchiness in siblings. Elowen FEELS like a sibling to Rowan... does that make sense?
I don't think they're too close. Elowen is very lovely!
Okay. Elowen = Cornish word name. It's supposed to be pronounced el-OWE-un or el-LEW-un, more commonly the first one, though I'm hearing it's pronounced EL-oh-wen everywhere now :( There is no 'when' sound at the end, so, to me, Rowan and Elowen sound near-identical. You could take off the 'R' and the 'El', swap them around and they'd still sound the same. I like the subtle tree connection, but I think they're way too close for siblings. Middle name, perhaps?