My worry with adding this script to the user's google account is the unknown - This is an issue that Google/Microsoft need to iron out. Not sure how easy removing the script would be, and whether doing so post-Google/Microsoft's fix wouldn't cause other kinds of issues, or whether Google/Microsoft's fix won't work due to the script's existence, when and if a fix does eventually come. And is there some unexpected unwanted behavior with team events/notices?
Being that this is a very surface level issue directly impacting end users, this is absolutely something that Google/Microsoft will need to fix. My hesitancy in applying the script fix is certainly born from ignorance, but it's also born from 13 years of working in IT. I may opt to continue re-adding the calendar for this one user weekly, at least for the next few weeks. If issues continue I may revisit the script workaround.