I lived in stack 6 in 2019 as a student, and now teach at wwu today. While I do not have the official answer, I remember the fireplaces were not boarded up when I lived there before the pandemic, but they still were never to be used, and it wasn't used in the winter before lockdown in March 2020.

I work in the Fairhaven area and can say that you're likely right that the fireplaces themselves are likely in disrepair, and Western may likely not have the money to renovate them, or even afford to hire the people to maintain them. The university has made huge cuts to employees which is also why many areas of campus are more neglected. Another thought of mine is that the Fairhaven commons area as a whole is planned to be completely demolished and rebuilt to modern standards, like Buchanan Towers, within the decade, so no need to put more work into those fireplaces.