Beth-horontheupper - The situation of this town is little known. It was eastward of Beth-horon the nether, and consequently not far from it.
Albert Barnes
Notes on the Whole Bible
Verses 5-8
From the abrupt manner in which the statements are introduced, as well as from their imperfect character, there is probability in the conjecture that some words have, in these verses, fallen out of the text. Few of the places are known for certain.
SDA Bible Commentary (limited)
Volume 1-7
5. Ataroth-addar. The mention of this town to the east is not easy to understand. However, if this Ataroth-addar is the same as the Ataroth of v.2, which it seems that it must be, then the border from Ataroth (see on v.2) would run quite largely in a southerly direction down as far as Beth-horon. This section, then, could be considered as part of the east border of Ephraim.