Baked cherry tomatoes with little salt like web recipe suggested but they turned out bitter not sweet and tangy like I have tasted in recipes

If they are bitter, sounds like the tomatoes burned. How long did the tomatoes cook and how hot was the oven? Did you add any oil? From what I can see in your photo, it looks like you overcooked and burned the tomatoes since I don't see any juice or oil on the parchment.

Try cooking until the tomatoes pop and look almost jammy. Use a generous amount of salt and add some oil too.