The healthStatus is one way only from SmartThings (ST -> HE). There is no HE -> ST solution since as you state, HE doesn't support this attribute in its native drivers. The topic has been discussed with Hubitat support a couple of times, but really went nowhere. Not sure why this concept is so difficult, but not my circus, and not my monkeys.
To add to a community driver, you only need to add to the metadata section and then some logic to set:
attribute "healthStatus", "enum", ["offline", "online"]
