These are part of the rituals of learning how a system works, in the same way interns get tripped up at first when they discover ^S will hang an xterm, until ^Q frees it. If you're aware of the history of it, it makes perfect sense. Unix has a personality, and in this case the kernel needs to decide what executable to run before any shell is involved, so it deliberately avoids the complexity of quoting rules.

I'd give this a try, works with any language:

  #!/usr/bin/env -S "/path/with spaces/my interpreter" --flag1 --flag2

Only if my env didn't have -S support, I might consider a separate launch script like:

  #!/bin/sh
  exec "/path/with spaces/my interpreter" "$0" "$@"

But most decent languages seems to have some way around the issue.

Python

  #!/bin/sh
  """:"
  exec "/path/with spaces/my interpreter" "$0" "$@"
  ":"""
  # Python starts here
  print("ok")

Ruby

  #!/bin/sh
  exec "/path/with spaces/ruby" -x "$0" "$@"
  #!ruby
  puts "ok"

Node.js

  #!/bin/sh
  /* 2>/dev/null
  exec "/path/with spaces/node" "$0" "$@"
  */
  console.log("ok");

Perl

  #!/bin/sh
  exec "/path/with spaces/perl" -x "$0" "$@"
  #!perl
  print "ok\n";

Common Lisp (SBCL) / Scheme (e.g. Guile)

  #!/bin/sh
  #|
  exec "/path/with spaces/sbcl" --script "$0" "$@"
  |#
  (format t "ok~%")

C

  #!/bin/sh
  #if 0
  exec "/path/with spaces/tcc" -run "$0" "$@"
  #endif
  
  #include <stdio.h>
  
  int main(int argc, char **argv)
  {
      puts("ok");
      return 0;
  }

Racket

  #!/bin/sh
  #|
  exec "/path/with spaces/racket" "$0" "$@"
  |#
  #lang racket
  (displayln "ok")

Haskell

  #!/bin/sh
  #if 0
  exec "/path/with spaces/runghc" -cpp "$0" "$@"
  #endif
  
  main :: IO ()
  main = putStrLn "ok"

Ocaml (needs bash process substitution)

  #!/usr/bin/env bash
  exec "/path/with spaces/ocaml" -no-version /dev/fd/3 "$@" 3< <(tail -n +3 "$0")
  print_endline "ok";;