Not sure whether it's the same issue, but I found a workaround that may help debug this:

https://blender.stackexchange.com/a/195973/35799

In T80544#1024622, @Michael Jastram (jastram) wrote:

Not sure whether it's the same issue, but I found a workaround that may help debug this:

https://blender.stackexchange.com/a/195973/35799

I observed this behavior on Linux with Blender 2.83.5.

I found a workaround:

1. Create a font strip in VSE
2. Set the font you would like to use (the preview does not reflect this)
3. Delete the strip
4. Perform an undo. At least in my configuration, the text is rendered in the correct font.

It is better UX to copy and paste it here. 😉 Thank you for the additional information. 🤗

I observed this behavior on Linux with Blender 2.83.5.

I found a workaround:

    Create a font strip in VSE
    Set the font you would like to use (the preview does not reflect this)
    Delete the strip
    Perform an undo. At least in my configuration, the text is rendered in the correct font.

Works

Worth mentioning it's not just when adding a new text strip - when you open an existing project, all text is immediately rendered with the default font, so it's a show stopper on your project. I thought the project file was broken somehow but when I downgraded to 2.8 LTS, the same project file opens with all the text correct. (Yep, I shouldn't be using the latest version of software on a long term project, but that's what you get when installing software from Add/Remove Programs in Manjaro)

Still broken in 2.92 and needs a Video Sequencer tag(why I can't add tags?).

Also Copy to Selected doesn't work for fonts, which is quite crippling, since users a likely to want all text strips in the same font for ex. subtitles. +Alt doesn't work either.