Yes, I see, the source can be switched with momentary buttons in some aircraft.
Now, you can download updated database file (SimVim.dat) and see the parameter configuration table.
New parameters are included:
HSI_Source_Nav1 => set for momentary button
HSI_Source_Nav2 => set for momentary button
HSI_Source_FMS => set for momentary button
HSI_Source_3-pos => change for 3-pos switch
HSI_Nav_Source => change for toggle switch (Nav1/Nav2)
HSI_Source_GPS => change for toggle switch (Nav/GPS)
HSI_Sync_CRS => set direct (RMI) course for momentary button
The same parameter are added for copilot HSI/EFIS
Also, you can select EFIS_HSI_Mode (Arc/Rose) as momentary button now too.
By the way, as I see, in the E175 model both (capt, fo) PFD display the same (pilot only ) information. Also, the Arc mode is not switchable?