Note that when self made it can be accidentally end up with too much “vegetal” taste to it. It’s been a very long time since I’ve made it so I forgot what my resulting recipe was that addressed that.
On heat tolerance, do some genetic thing where people get one, two or three receptors[1] which give different sensitivity to different people. I had a GF who would struggle with the level of capsaicin I literally wouldn't even notice. I knew a guy who would snack on scotch bonnet peppers straight, which would be impossibly agonising for me.
[1] from memory, doubtless incorrect as well
But "acı" can also mean bitter. You have to look at the context to understand. However things can both be spicy and bitter. In that case it gets complicated :)
Perhaps the lack of a dedicated mapping to "capsaicin sensation" stems historically from England's reputedly bland cuisine...
England's bland food is a relatively recent development, much more recent than the language.
https://edmundstanding.wordpress.com/2020/05/28/hot-peppers-...
Thank goodness for immigration.
But I don't think it's fair to call UK food bland. Done properly it's very good, but what it's not (usually) is heavily seasoned. In no way does that require it to be tasteless, and done properly it isn't.
There is a reason there are thousands of Indian restuarants in England and approximately zero English restaurants in India. ;0)
Thankfully, food has improved vastly in the UK since the 70s.
personally, I'd add a little more than bell peppers, which tend to have a more vegetable flavor. there are some Italian peppers that have a nice sweetness without heat, for instance.
if you're looking for more of a sriracha flavor, add some garlic in there! there's just as much of a world of peppers to explore that isn't burning hot as there is super hot varieties.
Also, check out Habanada peppers.
https://heatonist.com/collections/hot-ones-jr-hot-sauces
A “super mild” line of sauces to introduce kids to hot sauce without overwhelming them. They might be a good starting point to see if she likes it.