Attach handle on a loose screw The handle of a micro wave oven broke.

I can't just order a replacement part because I can't even attach the new one. 

The problem is that the screw heads are somewhere on the interior side of the door, which cannot be disassembled (non destructively at least). I wouldn't even do it because of safety reasons.

I have access to the threads of two loose and captive screws to work with (indicated by the two red lines on picture one). The screws are not machine screws, but screws for plastic like in the attached picture.

The plan is to 3d print the plastic part of the handle and reuse the front aluminum cover.

I don't want the handle to be loose, so I'm looking for suggestions to attach the new handle. I have a lot of ideas, maybe I will share them later if they are not mentioned at some point. The main problem is: how to attach something when all I have to work with is a loose, non machine screw ?
You are facing 2 problems in this case:

Material choice
Design

Material choice
As far as I can see, this is an oven that can heat its interior to roundabout 250 °C, which means that the door will radiate a lot of heat. This needs special high-temperature plastics to withstand - PLA and ABS are not an option for this!
I would suggest looking for PEEK (stable at ~260°C) or a high-temperature resin print in this case, as there are some resins which can withstand much higher temperatures after curing. Note that PEEK is traded usually for above 100 €/kg and needs a specialty printer. Even the less stable PEI filament (works under 170 °C) needs a specialty printer: All metal hotend and 350-380 °C extruder are needed!
Design
The plastic screws you show are self-cutting plastic screws. if their head is accessible, they get screwed into holes that have a bore large enough for the center.
If the screw head isn't accessible, for turning but can be pressed down, then one could opt to use high-temperature resin to cure inside oversized holes over the screw. This is not an option if the screw can't be pressed into the part though, as then the handle always will rattle.
Repair?!
Note that you might be able to access the screws with a little work, if you have the right tools and manual.