Their ultimate fate, in the limit of infinite time, is to crystallize.

Alright, but the article is talking about long to infinite timescales.

Long to infinite timescales for it to crystallise, that is to solidify. This is explicitly noted in the abstract of the paper the article is based on. I understood the "short timescales" on which it "relaxes towards the liquid state" to mean more than one human life time based on figure 4 (the image also shown in the article), but not so sure about the 10ky cited in the OP though.

The discussion above was about church windows and that is not caused by glass flowing.

Yeah that might indeed be an urban legend, could be manufacturing artefacts as claimed here. However I will note that the version of it I am familiar with isn't about "bull’s eye marks, warps, and lines" as that article states, but specifically about old windows being thicker only at the bottom.