If your computer is playing perfect GTO where the rules are the same for both players, it is essentially assuming that the other player is also playing GTO. To do otherwise would mean that it would be playing exploitively against the other players assumed non GTO strategy which would make the computer itself exploitable. But you can stipulate to the computer that the rules of the game have changed such that the opponent MUST play certain hands badly. For instance he must always raise preflop with 72, 83, and 92 offsuit. Given that, the computer will alter its strategy from the original GTO strategy to a revised strategy based on those new assumptions.

My question is what are those new assumptions? Does it assume that it is playing a handicap match with Doug Polk who is required to make those raises? If so, its counterstrategy has to be against the Polk strategy that will include far more changes than just his preflop raises. Polk will adjust strategy on every street because of the requiredplay of those three hands. And if he is doing it perfectly, his adjustments will include his knowledge that you adjust.

Is that how these nodelocking machines work? If the answer is "yes" that is a feather in the cap of the programmers. But there is a problem. When you notice that a player is raising a lot preflop with hands that he shouldn't, running to your computer to ask how you should adjust to this will not result in finding a great counter strategy. Unless, of course you are sitting across the table from Doug.

Yes, when you nodelock computer just finds new equilibrium under new constraints.

There are a few problems with it:

1-Player is just playing one node badly, after that he is playing perfectly.

2-Both players know that one player is forced to played badly and that other player is trying to exploit that. This is unrealistic because in real game, player making the mistake is generally unaware that he is making a mistake or that you are exploiting it (if he was aware of it he would just stop making the mistake).

3-If you lock later streets solver will alter strategy of early streets a lot. For example if you force BB to DB every flop in singe raise pots, solver will start folding and 3betting a lot pre just to avoid handicap situation as much as possible.

Yes, that's how they work.
Nodelocks are not the end all be all, but they are useful

The tldr answer is "yes". It adjusts its strategy in all nodes (and for both players) to compensate for the node lock. The solution that it comes up with a nash equilibrium to a modified game. The only way to exploit the node locked solution is to deviate from the node lock.

To address the problem that you stated - you can lock multiple nodes. This would prevent the solver from compensating for its mistake in other parts of the tree.