Agreed. I could fix this for me but that doesn’t help anyone else. ST could change it in one minute but the handler would break for the other dimmers that don’t use the same mapping for parameter 3. I suppose the correct way to deal with this is for the handler to identify the particular dimmer and implement the indicator control appropriately for each model. I’m still learning this stuff but I think there is information in the ‘Manufacturer Specific’ command class that would identify the dimmer in such a way that the handler could cross-reference to the appropriate control of the indicator light options. More than 1 minute, perhaps 
I suppose you could also create a specific handler for this dimmer and publish it separately. Ultimately, you’d probably need a few handlers to cover the variation in the treatment of the indicator light across brands. I’m not exactly sure how the discover process works and how ST decides what handler to use when you don’t specify one. . . it would nice if the ST platform would be able to correctly connect dimmers to one of a few possible handlers.
So, if ST should be addressing this, what is the process? Who decides if there should be one handler with conditional branches or 3 or 4 individual handlers for the different dimmers? Since this is, admittedly, a small issue, will it ever get addressed?
BTW, if anyone else is watching, here is a direct link to the thread mentioned by @codytruscott