Is "<leader> key" supposed to be able to call keybindings in keybindings.json?

Everything is up to date

I have a handy keybinding that opens the file explorer and closes it if its active (its a hack because there's no toggleExporer command built in). I had to put this in keybindings.json because of the conditional ("when")

keybindings.json

  {
    "key": "ctrl+'",
    "command": "workbench.view.explorer"
  },
  {
    "key": "ctrl+'",
    "command": "workbench.action.toggleSidebarVisibility",
    "when": "activeViewlet == 'workbench.view.explorer'"
  }

I'm having no luck being able to call it using a leader key

    {
      "before": ["leader", "d"],
      "after": ["C-'"]
    },

However I have no problems with using the leader key with remapping vim keys and calling vscode actions:

    {
      "before": ["leader", "d"],
      "after": ["C-f"]
    },
    {
      "before": ["leader", "s"],
      "commands": ["workbench.action.files.save"]
    },

Start with the keybindings.json examples and compare the leader mapping that triggers C-' with the mappings that trigger C-f or a VS Code command. Trace how leader mappings dispatch keybindings and define done as making the conditional explorer bindings callable through the leader key, with coverage for the reported mapping behavior.