I’m assuming that you want to know where Central Buildings were.
My research suggests that Central Buildings is the former name of the block of buildings now 165-175 Conway Road.
First of all the sequence of 1921 records is:
Oswald Road
St Margarets Road
Central Buildings
Ronald Road
Glanmorfa Terrace
Riverview Terrace
Glanmorfa Farm
Although this doesn't establish an exact location, it does define the general area. The modern 165-175 Conway Road form the block between the junctions with Oswald Road and with Ronald Avenue.
Unfortunately there are no 25 inch maps at NLS for Llandudno Junction to tie this down any further.
Newspaper references to Central Buildings begin in 1903, suggesting that they were built around that time. In that year there is this advert indicating that the properties at Central Buildings consisted of shops with houses (presumably upstairs). Notice also that other lots in the sale from a single bankrupt owner are located in Oswald Road and Ronald Road.
There are many later newspaper adverts mentioning business for sale in Central Buildings up to the 1950s. The block on Conway Road fits the description of shops with dwellings.
11 September 1903: North Wales Weekly News