As far as I can tell from the code, I don't think the ServiceContext will apply to the ParametersSummary. A solution to this could be to add a subscription filter in the ParametersSummary table key part like this:

Max|34906/637:1007:filter=xxx|34906/547:11102:filter=xxx|Alarm

As I understand it though, you also want to automatically take a summary of several parameters of included elements?

If you want all parameters' alarm color of all included elements, this is just the service state, but if you automatically want to iterate over all elements and get the highest alarm states of SPECIFIC parameters, that doesn't seem possible. If that is the case, I'm curious what the exact use case is here.

Eventually, all of the above could be achieved with a combination of the BackgroundColor shape data and executing an automation script that outputs a variable (e.g. a color or an alarm state to be combined with the "[color:Severity=...]" placeholder) upon opening the page. An example of the script execution that outputs a variable can be found in the inspire workshop video: https://community.dataminer.services/video/the-latest-and-greatest-of-visual-overview/ (it actually also fetches the elements in the service just like you would do).