Firstly, I don't consider
Imogen to be eccentric but it is quite popular over here (Britain) so I'm used to hearing it. I really like your other combos, more so than
Theodora and
Edmund but I'm not sure that they are that different in style.
Rowan Thomas - I like it.
Rowan seems to be very popular on this board.
Lachlan Samuel - Again, I like it.
Lachlan is very popular in Australia so I think of it as being an Australian name.
Eamon William - The only men I know named
Eamon are middle-aged so I feel this combo sounds a bit dated. Also, I say Ay-mon and this is the only way I've heard it pronounced. I can't see where the extra syllable comes in.
Bronwen Elinor - like it although I prefer
Eleanor.
Aisling Joan -
Aisling or
Ashling is gorgeous, very pretty.
Joan is a mundane frumpy sort of name to me which brings the combo down.