Have the STW Romulans be "Debrune". The only reference to the Debrune is a throwaway line from TNG Gambit Part I about being an ancient Romulan offshoot, so there's room for re-interpretation there. You can say that this Debrune civilization is located near Romulan space, so it can be assumed that sometime after Balance of Terror the Debrune joined (or were annexed into) the Romulan Empire. And since it's already common knowledge at this point in the timeline STW takes place that there are several Vulcanoid civilizations out there (whose ancestors rejected Surak's teaching and left Vulcan), it works.
Now the question I have is... what type of Klingons are going to appear in STW? I bet they do what Picard did with the Romulans and just mix it up. You'll see some Disco Klingons, some original movies/TNG-era Klingons, and several somewhere in between. I liked the look the K'vort Klingon character from the Disco season 2 final episode (played by Disco makeup department head Glenn Hetrick) - it was a great mix of the Disco and original movies/TNG-era elements.