in GW#1 the range is still too small... if it's fixed, shouldn't I find it there?
Yes. Though that bug report is so old that it was still under the old changelog policy where I did not post all such minor fixes and changes to it (like I do now; each and every small change should be posted to the public changelog) so I cannot exactly tell what has been changed based on that report. I see from that thread that at least a lot of new engine variants were added, but if you read my comments on the thread I had some trouble understanding what the actual issue was and what exactly would require a change.
At the moment the MD-88 shows a single weight variant, and it has 67812kg MTOW and range points as follows: max payload range 1100nm, 15000 kg payload range 2100 nm and zero payload range 2700nm. So the MTOW is exactly the same as in the docs you posted - but I see the extra fuel tank variant is missing (72tn variant, ref. pic posted on 12.02.2014, "MD-80 twin jet family"). ...so all in all, from what I see that the only changes still required would be the extra tank variant for both -87 and -88?