Yes there is still semaphore signaling at Portrush (it’s a 3 platform station so there’s quite a few). Not sure about any working semaphore distants though. I have a feeling the only distant is now a colour light signal. Could be wrong though.
These are the only semaphores left in Northern Ireland. They seem likely to remain for the foreseeable future as the station is just in the final process of a major refurbishment, and there’s been no change to the signals. Indeed one of the semaphores has been temporarily removed to be repaired.
Like Stranraer, Portush signal box is switched out most of the time, save when there are special workings.