en_tn/ecc/04/07.md

I returned and I saw something meaningless

Possible meanings for "returned" are 1) he returned to thinking. Alternate translation: "I thought again and and I saw something meaningless" or 2) he returned to seeing something meaningless. Alternate translation: "Again I saw something meaningless"

under the sun

This refers to things that are done on earth. See how you translated this in Ecclesiastes 1:3. Alternate translation: "on the earth" (See: rc://en/ta/man/translate/figs-idiom)