XLIFF file type enhancement or other ideas

Maybe somebody in the community or among the developers can help. Here what I’m looking for:

We have a request from a customer using XTM who sends us XLF files (currently 1.2) to be translated in Trados (for historical reasons...). For the translation, we will receive in the XLF the context of the segment (like headline, paragraph, table, …) and we would need to display it in Trados:
-    Best would be in the context column where the XLF filter currently writes TU / Translation Unit. Maybe there’s already an existing implementation in the filter itself but I couldn’t find any information about this.
-    Acceptable would be to display the information as a comment
-    Or in the preview box, near the Alt-Trans information
-    Last option would be to create a custom pane but that would mean we need to roll out a plugin for the vendors
Maybe you have some more ideas what is theoretically possible.

The next questions would be:
-    Is it possible to extend the XLF file type filter with such context information in the context column?
-    Is it possible to add comments with the API on certain segments? This would be an external application to run over original xlf and sdlxliff for example?
-    Is it possible to set up a custom xsl file for preview in the XLF file type, or here again, to extend the original filter to be able to do this?

One last point about the status/match icon displayed between source and target, how is the mapping between the match values displayed in Trados and the “state-qualifier”s used in the xlf. We already noticed that exact-match=100% and leveraged-tm= 80%m but don't know the rest yet. The match value in the alt-trans doesn't seem to be considered at all.

Do you have any hints?

With kind regards from Berlin