Surely the signs are the wrong way round, the English should be at the top in the darker bold font, as that's the language understood by the vast majority of passengers passing through busy stations like Cardiff. The Welsh should be in the smaller grey font at the bottom.
Looks like some foreign bilingual sign, that you'd find at a Trenitalia station, rather than a British sign where English is the main language.
Even in Sud-Tirol where the inhabitants mostly speak German, Italian is still the main language on all the signs, with the German in the smaller font.