en_tn_lite_do_not_use/2ch/07/09.md

the eighth day

The word "eighth" is the ordinal form of "8." (See: rc://en/ta/man/jit/translate-ordinal)

a solemn assembly

This was a special religious gathering.

they kept the dedication of the altar

Here "kept the dedication" is an idiom meaning "celebrated the dedication." (See: rc://en/ta/man/jit/figs-idiom)