The full name of the place is Bryn Meurig Buildings (if you look at the 1901 Census, you will see that is what was used then). My postcode finder suggests that only numbers 3, 4, & 5 are still standing, however number 2 may still be there but with a house name.
Bryn Meurig is the name of the hill on which the parish church stands. Bryn Meurig Buildings are on Lombard Street fairly close to the Church.
If you look here:
Map.
It gives a general idea of the location.
The easiest thing for your brother to do might be to head for the area around the church and see if he can grab a friendly local to pinpoint the exact location for him.
Strange thing about your Great grandfather in 1891, he could speak only Welsh and his wife could speak only English - I wonder how they communicated?
