There are more precise methods than GSM Cell ID
"Multilateration: More advanced systems use the signal strength and timing from multiple adjacent cell towers to triangulate the phone's position. This is more accurate in urban areas where cell tower density is high."
https://en.wikipedia.org/wiki/Mobile_phone_tracking#Network-...
In many cases accuracy better than 200 meters can be reached.
"Database correlation method for GSM location". IEEE VTS 53rd Vehicular Technology Conference, Spring 2001 https://doi.org/10.1109%2FVETECS.2001.944052
Absolutely, I just don't know that this can be achieved over the Diameter/SS7 network between carriers, which the report was alleging access to the RAC/TAI and Cell ID's. So if the threat actor has different level of access to an individual network, we're talking a completely different analysis.
Sorry if I was unclear about that.