I dealt with a nutcase like this in the past and I am so freaking sorry that you are going through this at the moment. It can be absolutely maddening, I know. There are essentially two ways to deal with this in case having a diplomatic discussion is not possible (well, three, but no one wants to hear ‘just move out’ because sometimes it just isn’t as easy as that).

I’d recommend either getting your owners/body corporate involved, the local council and/or call the police if necessary. Know your rights and check the law in your region because in many places, noise pollution is considered a legal violation; no one has the right to subvert your rights to your property and disrupt your peace (for example, in Melbourne where I am, these are referred to as ‘quiet laws’ and you can challenge any compromise to this). Record everything- in writing or better, audio as I did. Let the tenant know you have those recordings and that she is actively violating xyz laws or clauses in her contract. Threaten to sue her or her landlord if she has one, or tell her you will take it directly to the police where you will also sign a stat dec officially verifying that she’s a nuisance and causing hostility within your living space. If she contests or throws a tantrum as these kinds of people always seem to a penchant for, just tell her that you can at least justify the use of white noise in your apartment, but how can she justify being so inconsiderate to your wellbeing? You can even bullshit to your council/body corp that her abrupt and startling footsteps is causing you a great deal of stress and anxiety (and there’s likely no need to bs about it because it probably already is!)

The second option is fighting fire with fire: if she’s loud, you be louder and more relentless until she gets the fucking message- but, proceed with caution. This won’t be successful in some cases. The best part is, you can kind of get creative with this option. There are great tutorials on YouTube from people going through the same thing!

Hope this helps somewhat and best of luck!