I raised a incident to SAP and got below reply:
Please keep the UID Number maintained in STCD 1 only but with the format CHE112954332 (without special characters and suffix HR/MWST, HR or MWST).
Validations will still work fine for the number. You can then extend the report used, to place special characters in between, this has also been the standard practise for other countries where special characters are taken care by reporting.
For suffix, we recommend you create a new tax type under Tax Classification and have 4 tax groups within e.g. HR/MWST, HR or MWST and the reporting can retrive these values to add the correct suffix.
Please confirm if someone already applied it.