The Idea in Brief
The lvnh should not have been pointed as levenah = brick, and chmh not as chomah = wall, as the Septuagint indicates. The reason is that the translators of the Septuagint had no editorial clues such as vowel points in which to discriminate Hebrew words and phrases in their precise meaning; in this respect, words with homophonic-sounding parallels to other Hebrew words in this verse had caused confusion in the translation from Hebrew into Greek.
According to Lust, et al. (2003), there are homophonic parallels for both the Hebrew nouns moon and brick, and the Hebrew verbs for decay and abashed. In other words, the homophonic confusion between these respective Hebrew words led to the current translation found in the LXX.
While they do not address the homophonic relationship between the Hebrew noun for sunshine with the Hebrew word for wall, a cursory check of the Hebrew word for sunshine in the Hebrew lexicon is חַמָּה, which is homonymic with the Hebrew word for wall, which is חוֹמָה without vowel pointing.
As for possible homophonic confusion with the Hebrew phrase וּבֹושָׁה (and [she] was ashamed), my observation is that the phrase is homophonic/homonymic with the Hiphil perfect, third person feminine singular of יָבֵשׁ (and [she] was laid waste), which speaks to the overthrowing of cities as per the following. Please note that this citation recognizes the homophonic relationship between both verbs! (Please click on the image to view the source online.)
The only problem with this last observation would be that the phrase would have to be “והבישה” instead of the received form, which is “ובושה.” In this regard, the LXX translators would have had to assume literary license to “stretch” one word into the other.
Finally, when viewing the Targum Jonathan to the Prophets, which appeared as early as the Second Century, the Jewish scholars understood that the words moon and sun were evident in the Hebrew when translating into Aramaic. The Targum appears below with the proposed translation.
23 And they will be ashamed who revere the moon, and they will be bent down who venerate the sun, because the kingdom will be revealed by the Lord of “hosts” in the mountain which [is] Zion and in Jerusalem even before the elders of the people in honor.
Note the editorial emphasis on “hosts” to refer to the Lord of the moon and sun, which are the “hosts” worshipped in heaven by those who are disobedient. Rashi makes the same observation of this Targum.
When the LXX translators used the Hebrew texts, they had no editorial clues such as vowel pointing to discriminate words and phrases from other homophonic-sounding words and phrases. In this respect, this homophonic confusion in this verse had led the LXX translators to “hear” brick for moon; decay for abashed; wall for sun; and laid waste for ashamed.
Lust, Johan, Eynikel, Erik, & Hauspie, Katrin (2003). A Greek-English Lexicon of the Septuagint (Revised Edition). Deutsche Bibelgesellschaft: Stuttgart.