jbxvt terminal emulator: adding WM_CLASS and increasing/changing font?

On other terminal emulators, I can use xprop together with grep to get their WM_CLASS. From that, I can add this value to .Xresources or .Xdefaults for adjusting fonts and other terminal properties. .xrdb .Xresources; xrdb -merge .Xresources (or .Xdefaults) would reset it.

Nothing shows for x11/jbxvt for WM_CLASS, There's WM_NAME(STRING) =, but using this value doesn't help with adjusting fonts.

How would I set WM_CLASS, so that the font settings can persist when I start jbxvt? Or how can I otherwise set the font on a program which doesn't have this value?

Here's what I have for .Xresources:
xvt*font: -*-courier-medium-r-*-*-18-*
jbxvt*font: -*-courier-medium-r-*-*-18-*
From that, xvt's value works, but jbxvt's doesn't. "XTerm" is a common class which works for a few terminal emulators, and for specific options available on those terminals. xvt has both "XTerm" and "xvt" as WM_CLASS.
The previous error from running jbxvt was:
Failed to load font: -*-terminus-medium-r-*-*-14-*-*-*-*-*-iso10646-*
Failed to load font: -*-terminus-bold-r-*-*-14-*-*-*-*-*-iso10646-*
this had a small font. Because of that output, I thought that, a similar line could be placed in .Xresources

From a search, I came across x11/xdotool, which sets WM_CLASS, but that value doesn't work in .Xresources.
xdotool search --name "jbxvt" set_window --class "jbxvt"

libx should be replaced by libxcb in jbxvt.

jbxvt -F "-*-courier-medium-r-*-*-18-*" fixes the regular font. So, to fix the bold font also, add that argument consecutively in the same line.

Using the font size number alone didn't work earlier. It seems like a way to set this more permanently would be available, since it uses that format. For the error message to simply go away, installing and configuring the terminus font would do that. Need the font increase, and want to stay with the courier font, preferably in a permanent setting, aside from setting it like that in .xsession.
I have tried jbxvt -F '-*-courier-medium-r-*-*-18-*' -B '-*-courier-bold-r-*-*-18-*' and it seems to work well.

#3 seems to have been edited.
I was thinking about using my shell profile alias to set it. That sounds good too though, for doing it that way.

If there's another way, but programs which have their settings changed by editing headers, usually don't have many other ways.