Depending on the heat level of the chiles you use, the salsa could end up being quite spicy, even after they are deseeded. Have a quick taste of the raw chile to see how hot it is. I found our salsa was spicy but it had a mellow, warm heat to it and was very pleasant. If you want a less spicy finish, add a few extra cherry tomatoes to the baking sheet or use less chile. Adding a sweet red pepper (capsicum) to roasted ingredients can also dilute the heat a bit while adding lots of flavour.