Say i have a sentinel on a roof not adjacent to the edge, can a figure on the ground see and be seen by the sentinel?

XXXXIXXXX
SSXXIXXAX
SSXXIXXXX
XXXXIXXXX

S= sentinel occupied area, A= figure with targeting question I= edge of elevated terrain, X= unoccupied elevated/nonelevated terrain

No. Nothing in the Sentinel or general Colossal figure rules indicate that Sentinels treat drawing LOF from elevated terrain to non-elevated terrain any differently than other characters, unless a character on elevated terrain is trying to draw LOF to the non-elevated Sentinel.