en_tn_condensed/rev/04/06.md

a sea of glass

How it was like glass or a sea can be stated clearly. Possible meanings are 1) a sea is spoken of as if it were glass. Alternate translation: "a sea that was as smooth as glass" or 2) glass if spoken of as if it were a sea. Alternate translation: "glass that was spread out like a sea" (See: rc://en/ta/man/translate/figs-metaphor)

like crystal

How it was like crystal can be stated clearly. Alternate translation: "clear as crystal" (See: rc://en/ta/man/translate/figs-simile)

In the middle of the throne and around the throne

"Immediately around the throne" or "Close to the throne and around it"

four living creatures

"four living beings" or "four living things"