“they are having the pope treat them very kindly and they don’t seem to appreciate it.”
The SSPX appreciates the pope’s kindness from very much. However, their mission is to safeguard doctrine like St. Athanasius in this time of diabolical disorientation.
Then they are failing. They already admitted that this isn’t a doctrinal issue.
If the principle they are defending is that the Latin is the only language that can be used to perform the sacrament of the mass, then they are gravely mistaken.