Pretty much, there are no shortage of ways to merge such data badly.

Many devices, uncalibrated and drifting, poor time normalisation to address counts accumulating when lingering, ... ffs they probably don't even adjust for cosmic or radon ...

( TBF the last two are pretty picky objections unless you're going hardcore geophysical professional )

Your general point is true, but in this case the devices are not really sensitive enough for radon to matter and the same is usually true for cosmic radiation.

When capturing open-air terrestrial tracks they are more or less uranium and thorium detectors.