en_tn/ecc/02/11.md

all the deeds that my hands had accomplished

AT: "all that I had accomplished" (See: rc://en/ta/man/translate/figs-synecdoche)

vapor and an attempt to shepherd the wind

See how you translated this in Ecclesiastes 1:12.

madness and folly

These two words mean basically the same thing and are combined for emphasis. (See: rc://en/ta/man/translate/figs-doublet)

For what can the next king do...which has not already been done?

The writer uses this question to emphasize his point that the next king will not be able to do anything more valuable that what he had already done. AT: "For the next king can do nothing...which has not already been done." (See: rc://en/ta/man/translate/figs-rquestion)

the next king...who comes after the king

"the king...who succeeds the current king." This was probably written by the current king, so "after the king" could also be translated as "after me." (See: UDB)