а вот в других местах пишут обратное
If moisture gets into stone wool,
its performance will be unaffected
Because stone wool does not absorb or hold
moisture, it remains dimensionally stable, meaning
the performance will not be affected by changes in
temperature and humidity.
In high humidity environments, stone wool ceiling
products do not sag, droop, or warp due to the
moisture.

вот ещё
https://www.diva-portal.org/smash/get/diva2:12526/FULLTEXT01.pdf
To sum up the most important facts about this report:

As the results of the simulator calculation show, the wall
construction with inbuilt moisture should dry up in the following year
cycle. There was not found an extreme amount of inbuilt moisture in
the specimens, which were taken from the openings made on the ´wet´
place on the facade. Their moisture weight ratios are comparable with
those, taken from the ´dry´ place on the facade. Wettest samples in the
applied openings were found in the opening situated 100 mm above the
horizontal joint between facade sandwich panels.
It seems there are some local problems with moisture on the facade and
not a general one. This could be caused by several reasons. For instance
- joints between sandwich panels were not closed properly. Also joints
around some windows were not finished at the time of taking
specimens on the building site; they were unprotected for days. This
also allowed driven rain to get deeper to the wall construction. Another
reason for the higher level of inbuilt moisture in some sandwich panels
could be their inadequate storing. And more, even though the building
was heated from October, condensation could occur.

ну вот исследование
https://link.springer.com/article/10.1007/s10973-019-08384-5
However, under normal conditions (relative humidity between 45 and 55%) as Jerman and Cerny’s research also shows the hard and soft stone wools’ moisture content is in the range of 0.01–0.02%, which does not cause major difference in the measured thermal properties [12]. Based on Keresztessy’s research [14], in the early 1990s and the now withdrawn Hungarian standard about designing of buildings and building envelopes [15], an additional 25% correction factor on the thermal conductivity was recommended. It was explained by the construction conditions for thermal insulation boards installed into flat roofs in a single layer with flat joints without mounting. Unfortunately, the standard’s value claimed to apply both mi

ну, 100% влажность на Кипре - это, вероятно, только на берегу
у нас 3км до моря - выше 60 не поднимается

да, а потом высыхает