Understand it is not Acer's call. The Windows end user license agreement (EULA) you have is with Microsoft, not Acer. And you agreed to abide by that EULA when you decided to keep using it after you built and installed it on your computer. Retail licenses do not allow installation on two machines and OEMs don't allow transfers.
So, technically, the only way it can be "fine" is if (1) it has been "uninstalled" from your self-built AND, it was not an OEM/System Builders license - which the vast majority of all Windows licenses are. And note "upgrade licenses" are tied to the original license, and thus original equipment too.
I just want you to know the facts so you can make an informed decision.
For testing purposes, I would go for it. If it works, then you will know reversing the polarity caused no damage. But if the plan is to keep using it, you should ensure you are legal by purchasing a new Windows license, if necessary, or installing one of the many capable Linux alternatives.
