Adapted lenses, with no electrical connection DO NOT HAVE FOCUS GUIDE capability. They only have peaking capability. I have an R, I have Nikkors and I have an F to EF ring. No "triangles"
It has been said, that an adapter with the right "chip" to fool the camera into thinking a lens is on it, may be in the works to provide that capability. Hope so! (but it aint out, as of today, that I know....)