@dzhimc: thanks for the information, unfortunately Health Check works only with a v2 Hub (I have v1).
Actually, I developed a “watchdog” SmartApp 2 years ago, for the same purpose SmartThings developed Health Check; may be they got the idea from me and a few others
Some progress information : my latest version of the FGK-101 Handler works pretty well, except that I am stuck with a last bug I cannot eradicate. It is nasty enough that it generates random spikes about 1°C in excess of or below the correct temperatures, so it makes all reported measurements “noisy”.
This happens only with the latest Z-wave+ / ZW5 version of the FGK-101.