Tornado siren sound during acceleration only

First thing I would check is the CVT - the Jatco CVTs are (kind of) known to fail due to intolerance of poor maintenance, lesser quality then the Aisin CVTs Toyota uses (which hold up a lot better because they have a starting gear, the Jatco doesn't). Some people put generic CVT or ATF trans fluid, which the Jatcos do not like, and that kills them. Open the hood and listen in the engine bay - this is a FWD layout, so the trans is transversely mounted to the engine. Have someone rev the car to 3-4krpm and try and pinpoint the noise, but focus on the CVT area first to rule out a bad trans quickly. It’s also not serviceable so you have to put a new trans in and it’s about as much as you probably paid for the whole vehicle. Parts and labor, even the part isn’t cheap as a DIY job. You can’t even trust used ones because someone probably killed it the same way.

Now this shouldn't need to be said but I kind of have to but if you have long hair, use a hair tie and pin any flyaways with pins - you don't want to be face to face with an engine bay over long hair.

If the sound is coming from the middle and not anywhere near the CVT, it may be with the engine (CV joint, pulleys for the timing belt, possible turbo failure), I would take the coils and plugs out and inspect them for damage or evidence of issues like oil consumption which will show up as black sludge on the plugs or cracked plugs. If that looks good, I would get a set of compact MEMS micrphones and place it on the trans, and a few places on the engine -- something like this: https://www.amazon.com/Steelman-06606-Ch...

You can probably get something cheaper, but check the reviews before you buy.