Not too sure about the too much sun, partly as not sure which cultivar type tree is and knowing PacNW weather. Tree seems fine where it’s at for now. Maybe dig up next year and reposition or box it.
Along the way one must decide, what height and type of tree is desired. Masculine or feminine or something in between. That’s what should be focused on right now. Take some time.
There are basically two schools of thoughts on maples and other broadleaf trees.
Chop and Pop. Keep tree in soil and hard chop, wait for something to pop out to be a new leader. Feed well. Repeat. Dig up each year and chop roots. Later down the line, pull out of ground cut branches off and regrow to create tree, Really good for developing chunky Tridents. (Japanese Maples dig and curate roots every two years.). Creates powerful larger trees
Clip and grow - keep in ground a couple years, let grow to girth up a bit. Dig up, curate roots aka Ebihara style. Put in box. Keep fertilizer values moderated. Use sacrifices to thicken trunk and branches as indicated. Pick up box every month or two and assess, clip and grow to build trunk, building short sections of branches and ramification along the way. Creates more refined trees.
btw Please modify your icon data to indicate which Vancouver (WA or BC) you are in. Makes a big difference to us.
Cheers
DSD sends