Roadsigns in Wales are bilingual. All official correspondence in Wales is bilingual. It is not unreasonable for non-public bodies in Wales to communicate in Welsh where requested.
Welsh is an official language within Wales. The Welsh Language Act 1993 places a legal obligation upon all public bodies in Wales to communicate using the Welsh language in addition to English.
Principalities are not precluded from being classed as a country (cf. Liechtenstein, Monaco, etc.) however Wales is not a Principality - it officially ceased to be such during the 16th Century when the Princes of Wales lost any constitutional role and the title becoming honorary. Unfortunately, even though the British Government is well aware of the status of Wales and uses the term "country" when making reference to Wales, until a few months ago nobody thought to communicate with the International Organization for Standardization (ISO) to update their erroneous entry for the constituent parts of the United Kingdom in their standardized list of country codes.
ISO 3166-2 now categorically lists Wales as a country.