Following are a number of back-translations as well as a sample translation for translators of 2 Chronicles 30:21:

• Kupsabiny: “So, all the people of Israel who had gathered in Jerusalem celebrated the Festival of bread that was not risen for seven days with much happiness. During all that time, the Levites and priests were praising and singing to him with all their strength.” (Source: Kupsabiny Back Translation)
• Newari: “The people who gathered in Jerusalem rejoiced seven days celebrating the festival of unleavened bread. And the priests and Levites played instruments loudly for the LORD and praised the LORD every day.” (Source: Newari Back Translation)
• Hiligaynon: “In seven days, the Israelinhon who were there in Jerusalem celebrated the Feast of Bread which Has-None of Which-Causes-to-Expand/(Without Yeast) with great joy. Everyday the Levites and the priests sing praises to the LORD, accompanied by the loud instruments being-used in praising the LORD.” (Source: Hiligaynon Back Translation)
• English: “The Israeli people who were there in Jerusalem celebrated the Festival of Eating Unleavened Bread for seven days. They rejoiced greatly as they celebrated, while the priests and other descendants of Levi sang to Yahweh every day, and played musical instruments to praise God.” (Source: Translation for Translators)