This patch:

--- a/roundup/cgi/templating.py Wed Jan 01 09:54:32 2025 -0500
+++ b/roundup/cgi/templating.py Wed Jan 01 17:35:03 2025 -0500
@@ -3407,6 +3407,9 @@
         alert("Your request is being processed.\\nPlease be patient.");
         return false;
     }
+
+    /* reset after 5 seconds */
+    window.setTimeout("submitted = false;", 5000);
     submitted = true;
     return true;
 }

will make the submit button work again after 5 seconds. I tested this in chrome and 
firefox with classic demo tracker (with 5000 replaced by 20000) using:

  open new issue
  submit empty issue
  get page with error message saying title required (2)
  use browser back button to go back to prior page (1)
    hit submit immediately you should see the please be patient message
  wait until 20 seconds has elapsed
  submit again and it should go through

(1) gets restored from the back/forward page cache and seems to also restore the
setTimeout. I am not sure if the time you were on page (2) is counted.
Per: https://web.dev/articles/bfcache#how-bfcache-works, the time on another page
is not counted.

For testing I ramped the 5000 to 20000 (20 seconds) to make it easier to
see the "patient" message.

So this might be a workaround. Exact timing delay, or making it settable TBD.