Hello,
On Capella Studio, contributing new tabs to the properties view is specified through the “ui.vptext” aspect (so in your vpdsl project) that will generate a .ui project during viewpoint generation. This contribution of a new Property View tab rely on an extension point (eclipse extension point) and not on the Sirius Properties contribution. To put it differently Capella Viewpoint technology does not rely on this Sirius feature and such integration have not been investigated nor it is tested.
As you pentionned it on your other message Are there incompatibilites between Capella and Properties View in Sirius Specifier - Yes or no? there is something to be investigated. I have opened an issue Capella Studio / Sirius Property View compatibility ? · Issue #154 · eclipse/capella-studio · GitHub. Do not hesitate to contribute to it.
Regards,
Arnaud