Match Filter in Time-Frequency domain instead of just Time domain. Redundant, or better?
Think of the time - frequency ambiguity of your matched filter like so:


Frequency ambiguity means it will respond to a range of frequencies
Time ambiguity means the response will be 'smeared' around the spatial location.


If you you have 0% frequency ambiguity, the matched filter must look like a sine wave and go on for ever, which in the frequency spectrum looks like a dirac delta.

0% time ambiguity is a dirac delta in the time domain.

So if you have a matched filter that is more than 1 sample wide in the time domain, then it already is ambiguous in both time and frequency domains.

If you are doing matched filtering of the envelope, then you are just looking at the modulating signal, and there is no need to look at the 2D time-frequency spectrogram.

If you want to match the envelop (modulating signal) and the base frequency, then you need a quadrature filter with a bandwidth around the range of frequencies you expect. A quadrature filter is required because it will make the response invariant to the phase of the base signal.

If you don't know the base frequency, a 2D time-frequency spectrogram will be useful as it will show you what frequency is being modulated. Essentially, the spectrogram is response of the signal - time axis - to a bunch of different (centre) frequency quadrature filters - frequency axis. 

TLDR:

The premise that the evelope-matched filter in the time domain is 100% localised is incorrect.