This was done for many years means the people of Jerusalem worshiped God with sacrifices for many years. The demonstrative pronoun This refers to offering sacrifices. This clause may be rendered “This was where things stood for many years” or “This was the situation for many years.”

But the inhabitants of the city transgressed means they disobeyed God’s Law.

An alternative model for this verse is:

• The people of Jerusalem worshiped you [with sacrifices] for many years, but then they sinned.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Esdras. (UBS Helps for Translators). Miami: UBS, 2019. For this and other handbooks for translators see here.