I'm curious - why did you buy it like that rather than another one with more balanced branches? I would let the shortened ones just grow out, but cut back the longer ones next March so they'll help even things out by re-branching, and you could also choose a couple of the left-sided ones to completely cut off if you want to. You could also tie a splint to the leader to help straighten it out for a season or two - just be sure you don't leave it on too long so the ties don't cut into the bark.

The headed back branches are a mistake. Cherries are prone to diseases from openings made by pruning cuts and dirty shears, also apt grow at right angles from heading cuts. And your tree is not intended to be used as a hedge. Replacements/remainders going in bad directions may have to be taken out at some point.

"When to prune

Early spring to* midsummer. Pruning in spring results in gummosis that may cause branch dieback.

Training and pruning

Train as a central-leader standard, ensuring well-spaced laterals. Remove unwanted laterals by rubbing out bud before they shoot, to prevent stem blemish at maturity. Train with a clear trunk no taller than 5ft (1.5m). To enhance the bark effect on lower limbs, clear sub-laterals to within 12-18in (30-45cm) of the main trunk, again by rubbing out buds. Do not prune established trees: it creates wounds that seldom seal fully and results in atypical growth.

--Brickell/Joyce, Pruning & Training

*Apparently supposed to be "or" instead of "to", if the next line is to make sense

Thanks to both of you--I think I will splint the leader and wait a season or two, then if it still seems unbalanced I may remove a few laterals.

(Lucy--I saw this tree at a local botanical garden but couldn't find it locally so I bought it by mail order, that's why I didn't have a chance to inspect it. And actually I've had very good results from this supplier in the past, so I'm kind of surprised.)