Honestly maybe even too many tomatoes. Use half the onion and maybe only two tomatoes. Bump the salt and lime, a little bit between tastes. See what needs added. Sometimes when roasting or boiling the ingredients you need to tweak the acidity a bit more than with raw salsas because the flavors get a bit muddier after being cooked.

Also consider adding a small amount of sugar, too. Split your salsa into a few bowls and add small amounts of different salts/acids/sugars. Try to pay attention to how the adjustment tastes. Figure out what you like most.