I cannot address with any certainty the "regularity" of "a כ/ך interchange with מ/ם," other than to state that such seems unlikely from a square script view (the letters look nothing alike), but at least feasible to me from a paleo-script comparison, which appears to show more similarity of the letters. Since the paleo-script is believed to have been in use up to the 5th century B.C. and Ezekiel composed in the early 6th century B.C., then its original composition was likely in paleo-script. So a change is at least plausible in that sense.
Warrant to Emend?
The real question is whether there is good warrant to even seek emendation, even if the paleo-script might have been more likely to allow such. The answer to that question, I believe, is a clear "no." There are at least two coherent solutions without calling for emendation.
First, it is possible that the third person masculine suffixed pronoun on מִמְּקוֹמֽוֹ does refer back to YHWH, and so a translation like the NKJV might be more appropriate:
Blessed is the glory of the LORD from His place!
Such a rendering would refer to the fact that wherever the LORD is manifesting, His glory emits from there, and that glory is (and is to be) praised. This makes sense, no emendation needed.
Second, it is possible that the third person masculine suffixed pronoun on מִמְּקוֹמֽוֹ does refer back to the glory itself, the grammatical gender of which is masculine, and so a translation like the ESV the OP gave:
Blessed be the glory of the LORD from its place!
This makes sense as well in the context of Ezekiel, as seen in 1:26-28 (ESV; bolding added for emphasis and discussion following):
26 And above the expanse over their heads there was the likeness of a
throne, in appearance like sapphire; and seated above the likeness of
a throne was a likeness with a human appearance. 27 And upward from
what had the appearance of his waist I saw as it were gleaming metal,
like the appearance of fire enclosed all around. And downward from
what had the appearance of his waist I saw as it were the appearance
of fire, and there was brightness around him. 28 Like the appearance
of the bow that is in the cloud on the day of rain, so was the
appearance of the brightness all around.
Such was the appearance of
the likeness of the glory of the LORD. And when I saw it, I fell on my
face, and I heard the voice of one speaking.
This is actually the encounter Ezekiel is having with YHWH that is continuing on in chapter 3, actually coming to an end in the verses under question (v.12-15). The "place" of the "glory of the LORD," from the context of Ezekiel, would then be that which had the likeness of a throne, upon which the one with an appearance as a man was "seated," and who, while seated, was emitting a brightness about him above and below his waist (which would be located immediately at the "bend" point of the human figure being seated, essentially the central point of the figure when seated on the throne.
What one finds, I believe, is that whether the pronoun should be translated "His" or "its" makes little difference, because in this case, the "place" of the throne is where the He who sits on it is, and the glory is emitting in brightness from Him and thus from this place.
In either case, an emendation is simply not needed, because the glory emitting from a location is clear in the context; and that such glory is linked to praise is not anything out of the ordinary (e.g. Ps 72:19; Isa 42:8; 1 Chr 29:10-11; Eph 1:12).