Luke sounds fine.
I know Matti is the Finnish form of Matthew. If you're going for an English version of a Finnish name, maybe Lucas, Nico, Tommy, Kai, Axel?
*****
And last of all an Admiral came,
A terrible man with a terrible name,—
A name which you all know by sight very well;
But which no one can speak, and no one can spell.
Robert Southey, "The March to Moscow"