ajsmsg78 is king on these types of issues, but my understanding on Mate 20x (which has some less clean ways to address recovery):
1) erecovery ramdisk is the methodology to use TWRP
2) recovery ramdisk is what is what has been pushed for stock or patched images to allow root.
I can get recovery_ramdisk, but see no boot.img in the extractor to patch. I know I'm missing the basics here.
Welcome to the suck. I'm fairly blind as well with Huawei rooting method. Things are much easier on the OnePlus side of the house haha. I too am having issues.