There have been several threads about cell broadcast alerts in the past. Can’t remember Jolla ever gave any clarity about this, so I would not count on that this time as well.
I can only tell my experience on this over quite some years: my Xperia XA2 receives about 40% of the alerts here in the Netherlands is my rough estimate. Why some broadcasts are picked up and some not: no idea. All I know is that I cannot rely on it.