I don't use the screen recorder that you mention.

If the audio and video are on two different files, then an app called YouCut can place (with a little practice) them in sync with each other.

I will give you the links to both YouCut, which is an excellent video editor without a watermark, and to the screen recorder app that I use, which also is simple to use and gives excellent results.

Just ask if you have any questions, I have been using both apps for a long time.

https://video-zip.en.uptodown.com/android

https://troones-recorder.en.uptodown.com/android

And as a possible bonus, I am using an older version of Screen Recorder that has no ads.

https://troones-recorder.en.uptodown.com/android/download/2247315

If you want YouCut to work without ads (they only appear when you are done editing, and then 'save' the final results) I suggest using a firewall to block internet access for the app.
This method can also be used for the more resent versions of Screen Recorder, or any other app that does not need internet access to work.

Be sure to delete the cache(s) of the app(s) after you block their internet access.

https://noroot-firewall.en.uptodown.com/android

 

Sure is.
Use the screen recorder I mentioned above, and re-record it.

Sorry, but this is the easiest method.

Another is to extract the audio from the file you already have, then try to sync the two files together using YouCut.

Use this app to extract the audio.

https://f-droid.org/en/packages/protect.videoeditor/