Using custom XML filters is not the ideal solution for handling the xliff files exported by WPML plugin in SDL Trados Studio.
From the SDL and your Community forums I read that an app is under development to convert these files and ensures compatibility and proper adherence to the xliff standard motto of "interoperability between tools".
As a paying, licensed customer for both your plugin and my translation software, I would like to request access to this application (even if beta and not stable yet).
Thank you for reaching us. My name is Przemysław, and I am working on the integrations between WPML and Translation Services (like SDL).
We are aware that WPML generates XLIFF files that are hard to process in SDL Studio. To help Translation Services to translate the content faster, we implemented a special "app" that is taking care of segmentation and removing HTML. Unfortunately, since segmentation is a complicated process, the "app" is a part of our connector between WPML and Translation Services.
Currently, we cannot add this to the WPML directly, because it would slow down everything and it might cause other issues.