If I open /org/gnome/shell/extensions/wsmatrix/ in dconf-editor, it
shows the settings as "Keys not defined by a schema".
https://github.com/mzur/gnome-shell-wsmatrix/blob/05fb910e66143edc2556accbd03746643547945b/wsmatrix%40martin.zurowietz.de/schemas/org.gnome.shell.extensions.wsmatrix.gschema.xml#L8

includes a path attribute, so I think the schema is correct.

Would adding a line like
https://salsa.debian.org/gnome-team/shell-extensions/gnome-shell-extension-dash-to-panel/-/blob/f4472ed6437f7d33a31633f71ba28287ad73196f/debian/install#L1

to wsmatrix's Debian package make the schema available to dconf-editor?