en_tn_condensed/isa/16/05.md

A throne will be established in covenant faithfulness

Here "throne" refers to the power to rule as king. The abstract noun "faithfulness" can be stated as "faithful." This can be stated in active form. Alternate translation: "Yahweh will be faithful to the covenant and he will appoint a king" (See: rc://en/ta/man/jit/figs-metonymy and rc://en/ta/man/jit/figs-abstractnouns and rc://en/ta/man/jit/figs-activepassive)

one from David's tent will faithfully sit there

Here "David's tent" represents David's family, including his descendants. Sitting on the throne represents ruling. Alternate translation: "a descendant of David will rule faithfully" (See: rc://en/ta/man/jit/figs-metonymy)

as he seeks justice

Seeking justice represents wanting to do what is just. (See: rc://en/ta/man/jit/figs-metaphor)