> but it is ungrammatical and a clear marker that the speaker is not native
You mean a native speaker might be ungrammatical when using their non-native language? That makes sense to me.
> Spain has 'Spaniard'.
Even so, you'll hear a ton of native Spanish people saying "As a Spanish person" or "As person from Spain" instead of simply "As a Spaniard", I'm not sure this is very surprising. If anything, that mistake makes it more likely they're a native than not, in the case of Spain, as the level of English outside of metropolitan areas is lacking at best, compared to other European countries.
You mean a native speaker might be ungrammatical when using their non-native language? That makes sense to me.
> Spain has 'Spaniard'.
Even so, you'll hear a ton of native Spanish people saying "As a Spanish person" or "As person from Spain" instead of simply "As a Spaniard", I'm not sure this is very surprising. If anything, that mistake makes it more likely they're a native than not, in the case of Spain, as the level of English outside of metropolitan areas is lacking at best, compared to other European countries.