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Many red, and Japanese maples will stay red, pretty close to year round, with some Japanese maples staying fully red year round. I would talk with your local nurseries or online nurseries to see what they have in stock. Most will ship worldwide.

The first summer is the most challenging for newly planted trees. Watch for signs of drought stress which include wilting of leaves and new growth, scorching of the leaf edges and dry, curled leaves.

Your tree is stressed and it could be watering issues. You need to check the soil and it's moisture level.
Use a garden trowel or spade to dig into the soil (near the tree) to a depth of 6 inches or so. If the soil is cool/moist to your touch, watering is not needed at this time. Check the tree again in another 4-5 days to determine when to resume regular watering.
A general rule is 10 gallons of water per inch of trunk diameter.
I would also suggest a layer of mulch to help keep roots cool and aid in moisture retention.

It was likely dropped from a different maple, or perhaps the red maple in the yard was pollinated with a nearby maple.

Even if it were self pollinated, the genome of a maple tree is so large and complex that it could never produce an exact copy of the tree from seed.

If you want an exact replica of that tree, you will need to take a cutting and root it.

This article will help: https://www.gardeningknowhow.com/ornamental/trees/maple/growing-maple-trees.htm

Without seeing images, my best guess may be Valsa cankers. These cankers will contain many small, white or grayish pimple-like bumps. This disease occurs when the fungal pathogen enters through injured bark caused by mechanical damage or pruning cuts. Valsa cankers also result in wilting and discoloration of the leaves, and branch dieback. Valsa cankers are most prevalent during periods of high humidity and rain, and trees that are unhealthy and stressed are more prone to valsa cankers. There is no cure for valsa cankers and control measures rely on cultural care. Provide enough water to the tree during periods of drought and ensure the roots have proper drainage. Immediately remove and destroy branches with cankers from the tree. Prune maple trees in the spring during dry conditions and disinfect pruning shears after each cut.

Begin by digging a trench around the root ball. As long as your tree is dormant, cutting the roots will not damage your Japanese maple.

In fact, root pruning will force the tree to produce more fibrous roots at the cut. This will help your tree become established in its new home.

The rule of thumb is 12″ of root ball per 1″ of tree caliper. Tree caliper is the diameter of the trunk, measured six inches above the soil line. A tree with a 2″ caliper trunk would need a root ball 24″ in diameter.

Japanese maple roots tend to grow more outward than downward. You will want to dig wide– at least as wide as the tree’s crown, if not wider.

Once your trench is done, it is time to shape the root ball for burlaping. If you are transplanting your Japanese maple immediately there is no need to ball and burlap it.

If you plan to keep it above ground for any length of time, you should protect the roots by wrapping them in soil and burlap.

Season makes no difference when planting your Japanese maple. You can plant them at any time. Time is only a factor when digging them.

https://www.gardeningknowhow.com/ornamental/trees/maple/care-of-red-maple-trees.htm

Certainly improper pruning can lead to diseases, pests and even stability of a tree.
Tree topping; as to what you describe actually can lead to more growth appearing and even growth at a faster rate.
You may want to have the tree examined by a qualified Arborist.
These links have more information.

https://www.gardeningknowhow.com/ornamental/trees/maple/maple-tree-pruning.htm