An excellent question that has been discussed at length and caused untold consternation for thousands of years. Here is my suggestion as to its resolution.
The text MIGHT be read that the eastern border of Naphtali was the same as that of Judah, namely, the Jordan River. This does not violate the text but allows the two territories to be separated as the map correctly suggests. That is, both had the same border (Jordan River) but did not touch.
The Pulpit commentary has another suggestion which is equally plausible:
We have it here clearly stated that Naphtali was bordered on the south
by Zebulun, on the west by Asher, and on the east by "Judah upon
Jordan." To Judah. These words have caused great trouble to
translators and expositors for 2,000 years. The LXX. omits them
altogether, rendering, "and the Jordan to the eastward." The
Masorites, by inserting a disjunctive accent between them and the
words that follow, would have us render, "and to Judah: Jordan towards
the sun rising," or, "is towards the sunrising," a rendering which
gives no reasonable sense. They unquestionably form part of the text,
since no version but the LXX. omits them. A suggestion of Von Raumer's
has found favour that the cities called Havoth Jair, which were on the
eastern side of Jordan, opposite the inheritance of Naphtali, are
meant. Jair was a descendant of Judah by the father's side, through
Hezron. So Ritter, 4:338 (see 1 Chronicles 2:21-23). It would seem
that the principle of female inheritance, having once been admitted in
the tribe of Manasseh, was found capable of further extension. But to
the majority of the Israelites this settlement would no doubt be
regarded as an offshoot of the tribe of Judah.