For a separator full-stop/period it should be followed by a space. Column 72 full-stops seem initially tricky, but a blank in column 73 deals with that.
When "looking at" COBOL programs I always rely on the compiler doing most of the real work, and that includes issuing diagnostics (so the output is assumed to be clean of relevant diagnostics, so no need to code for those situations).
However, I guess something I didn't think about is that 123. is a valid numeric literal. Even if that gets reported, it is probably a good idea to get it "fixed"