There is no blanket international law against all forms of discrimination, so there is no way to make an official determination. It might be possible to do so in a specific case for a particular kind of discrimination, so you have to find what treaties Tratatoria has entered into. The International Convention on the Elimination of All Forms of Racial Discrimination is a good place to look. It defines racial discrimination as
any distinction, exclusion, restriction or preference based on race,
colour, descent, or national or ethnic origin which has the purpose or
effect of nullifying or impairing the recognition, enjoyment or
exercise, on an equal footing, of human rights and fundamental
freedoms in the political, economic, social, cultural or any other
field of public life
Tratatoria may have acceded to this treaty without reservations, then it might be enforceable against the government. To find out, first you would have to determine a specific violation. Most likely, this act is not already prohibited by the laws of Tratatoria, and the dispute would be over their failure to create such a law. In that case you would have to officially pursue a resolution with the Committee on the Elimination of Racial Discrimination (Art. 11). That however requires that Tratatoria has accepted Art. 14, whereby individuals have standing. There are so many possible escape clauses that Tratatoria is probably not subject to this treaty on this point, but let's continue.
As the complaining party, you would want to look for precedents, many of which are summarized here. This is a long document which you would have to study carefully, and a violation is found in only about a quarter of cases. Some examples of findings of violation are Koptova v. Slovakia where certain villages prohibited residence of Roma people; L.K. v. Netherlands where the government failed to prosecute violation of already-outlawed acts. IMO there is no precedent under this treaty that suggests that the act is illegal, so then you would have to search for a different treaty, if any (e.g. EU law, if Tratatoria is a member).