Don't worry too much about it, I think Elspeth is not really in danger of being a Mary-Sue. The way Eppie wrote Gwenonwyn, on the other hand... But that was the whole point, wasn't it.

I feel you'll have more trouble getting some depth into Finlay's character. Next chapter, maybe :-) We haven't seen much of our heroic duo yet.

best wishes,
cloe