Let's start from scratch.
There are 3 different methods for OTA
- Arduino IDE
- Web Browser
- HTTP Server
This link should give you an overview what comes with the ESP Core for Arduino:
https://arduino-esp8266.readthedocs.io/en/latest/ota_updates/readme.html
In your entry post you write you don't want to use Arduino IDE OTA, and you are looking for an alternative for Async elegant OTA.
So you might have a look at the default Web Browser option or the HTTP Server OTA.
Imho all 3 default options are working. I can't imagine that any 3rd party wrapper will make it more stable. I would stick to the plain functions/examples from the ESP core.