I can no longer speak for the JW mindset since I've not been a Witness for well over a decade now.
Besides, Galatians isn't understood as teaching "justification by faith in Christ" without works by either Jehovah's Witnesses or "Christendom" in general. Why not? The issue in Galatians is not actually that of adhering to the Mosaic Law--according to mainstream interpretation--as much as it is to the practice of circumcision as given to Abraham before the Law and how those advancing the idea were shortsighted not only about but Christ but about what they were preaching. And the JWs don't believe you can have one without the other anyway in the salvation process.
The current explanation favored goes something like this: Paul's peculiar identification of those demanding adherence to certain Mosaic Law requirements and attaching it the message about the cross (or "torture stake," if you prefer) as "Judaizers" suggests that these persons were not Jews, per se, but converts to Judaism and late-comers to the gospel message at the time Paul was writing. Some suggest that they were Essene prosolytes.
Paul advocates the efficacy of actions or "works" as an essential and normal by product of faith. How? He corrects his audience by telling them that the act or "work" of circumcision was given to Abraham by God as a verification or physical sign that Abraham's faith was authentic. By this example Paul reasons that it is faith that circumcision is signifying, but faith in a promise, not in the Mosaic Law. (3:18) Paul was not teaching that circumcision itself was forbidden to Christians, but that its connection with the Mosaic Law promised no means of justification for the individual. If they were going to submit to the procedure in the belief that they were thus somehow fufilling the Law, they were mistaken. Seeking to be justified by the Law would mean living all of its demands perfectly without need for Christ, not just circumsizing themselves.--5:1-3.
While that might argue against "justification by faith in Christ alone" in the minds of some, it is not the point the apostle is making. Fulfilling the Law required the "work" of love because, like circumcision which typified it, authentic faith in Christ calls believers to this type of service. (5:13-14) Such type of love goes beyond the mere demands of the Mosaic Law and, by comparison, is a life of freedom from ritual observances as a result. Freedom in Christ is the main point.
I didn't come up with this that I wrote you, now. This is a culmination of several years of study on the subject of religion, and it is based on the current understanding of "salvation by grace alone" that is now the shared understanding in so-called "Christendom." (I had to pull out a lot books to get this typed up, and I may not have done it justice in my attempt.) Several Bible versions have this information or something like it in their introductory notes to Galatians, and I just combined a lot of the shared points. To repeat, I may not have done a very good job because I can't say I'm affiliated or even familiar with the religion of all those involved.
Lastly I can only add that JWs believe their system of religion is not out of line with this understanding, and in many ways they are correct. Granted their understanding of these points is greatly out of focus by comparison, mind you, and therefore some of these conclusions have been out of reach as a result of such short-sightedness; but you cannot convince them otherwise that their view is muddled or in any way in conflict. You will also not get far with others who still adhere to the "faith alone" argument either, since they also view a conflict with these texts as impossible.
And when you think something is impossible, you don't investigate the subject further. This is why religious debate in itself is pointless as it does nothing to correct and disarm any attitude that prevents reason from coming through. Without that being done, the best reasoning is lost from the get-go.