Why cannot I type the 'tréma' or 'accent grave' with my 'Canadian French input method'?

I am trying to effect these graphemes herefrom on Windows 10:

Other letters are accessible via "[" (square bracket), which works as a modifier.

• accent circonflexe: use "[" followed by a letter under accent
  • tréma: use Shift"[" followed by a letter under accent
  • accent grave: use Right-Alt"[" followed by a letter under accent

And finally, æ and œ are accessible via Right-Ctrl:

• æ - RCtrl"a"
  • œ - Rctrl"e"

I can produce only the circumflex. The other combinations fail for me:

Pressing and then holding SHIFT + dead key + i produces: Î.

Pressing holding SHIFT + dead key, and then releasing these before pressing i, produces: î.

Here is my settings in Control Panel:

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