In options, while remapping keybinds, under building selection, you can choose a keybind to select all Monasteries/Mosues/Preyer Tents. I chose Shift+Q. While playing HRE, when Rechnitz cathedral is built, this keybind selects not only the Rechnitz, as it should, but also all Outposts. (not sure why outposts specifically, but it does)
Thank you very much.