Sorry, my first sentence had the typo of having an extra 都 in there. I actually know 不 vs. 唔, 了 vs. 咗/喇(I think) already (made me feel kinda stupid even though I already have learned that). But thanks for the explanation for 不得了. Also, 不得了 feels more like a preconstructed grammar phrase rather than just combining 不得 and 了 together. And I got the "extremely" and "exceedingly" from the dictionary definition plus my feeling of it.
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