It's not just whether a given tree can "recover" from such poor pruning, it's what the long-term ramifications will be; All those stubs left all over the place will indeed likely have previously dormant buds "released" by the removal of the buds at the ends of the branches-the parts that are now gone. So far so good-the plant will appear to fill back out with live foliage. But the tree can't compartmentalize when branches are lopped off willy-nilly as seen here and consequently, there will very likely be a pocket of decay at the ends-or what are now the ends-of each branch so severely truncated. Even this might not matter so much if this is a species that matures at a low height, etc. It will be full of funky things but nobody will ever know that except for the OP and us readers, lol. But if this were a tall-growing species, having all that decay left up in the crown quickly becomes hazardous. Around here, the prime example of what I'm talking about are large, old silver maples, growing under wires, where the powerline clearance contractor has used less than stellar technique, leaving stubs behind. In each and every such case, regrowth of new sprouts has been explosive, but way back where the random cut was made, there is a well-defined pocket of decay, which can now travel down through the branch and even get into the main trunk. None of that might matter here if the OP keeps this tree small somehow. But that by no means should be used as an argument that this pruning was acceptable.

I'm not sure it is in danger. It looks green. If that is the root ball, it's not planted too deep. Couldn't you just sweep away the excess mulch, trim off any metal or burlap around the root ball water it, deal with any girdling roots, (There are advantages to having the rootball out of the ground!) then build a raised bed/berm with a gradual slope around it?

I would just remove the suckers from the bottom. Technically CMs are shrubs, so the mulch shouldn't cause too many problems. You could run a lawnmower over the mulch, and remove the adventitous roots, but this will likely create more suckers, making it more maintenance. See the link below for proper pruning. ==>>>http://thedailysouth.southernliving.com/2009/02/24/what-concerns-p/

under severe stress many plants.. including trees can shed all their leaves.. and then releaf .. ergo.. do not start cutting on the thing for the rest of the season ... if later the pieces still appear dead.. well.. dead is dead.. and start pruning ... i would leave it int he pot.. learn to water it properly for a tree.. and plant it in the next proper planting season.. a tree that is trying to releaf.. should not be stressed more.. by repotting or planting now .... see link below..regarding timing.. and everything else ... ken ps: and it appear that pot is about half full .. and i wonder why ... though i do not recommend repotting or adding soil now ... ken https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub