The heart here represents the emotions. Doing something sincerely or completely is spoken of as doing it with all one's heart. AT: "I will sincerely thank you" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Possible meanings are 1) "in spite of the false idols that exist" or 2) "before the heavenly assembly," which means "in the knowledge of the angels in heaven."
Bowing down is a symbolic action that represents worship and giving honor. AT: "I will worship you" (See: [[rc://en/ta/man/translate/translate-symaction]])
# give thanks to your name
Here the word "name" represents Yahweh himself. AT: "give thanks to you" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# for your covenant faithfulness and for your trustworthiness
The abstract noun "faithfulness" can be translated with an adjective. The abstract noun "trustworthiness" can be translated with a verbal phrase. AT: "because you are faithful to your covenant and you are worthy of people trusting you" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])
# your word
"what you have said" or "your commands and promises"