I did some quick researching on the matter.
Munka is vibrated Munyaka. If we assume that the "y" here is interchangeable (in written form) with the "i", we have Muniaka. A combination of Muni (मुनि) and Aka (अक).
मुनि
múni [ muni ]
m. ( accord. to cf. Uṇ. iv, 122 fr. √ man ) impulse, eagerness ( ? ) cf. RV. vii, 56, 8
( prob. ) any one who is moved by inward impulse, an inspired or ecstatic person, enthusiast cf. RV. cf. AV. cf. Br.
a saint, sage, seer, ascetic, monk, devotee, hermit ( esp. one who has taken the vow of silence ) cf. ŚBr. etc. ( with hṛdayeṣu sthitaḥ, the internal monitor or conscience cf. Mn. viii, 91 )
a Brāhman of the highest ( eighth ) order
[Source: https://www.sanskrita.org/wiki/index.php/muni?setlang=es]
अक
á-ka [ aka ]
2 n. unhappiness, pain, trouble TS.
[Source: https://www.sanskrita.org/wiki/index.php?title=aka]
So it would be a combination of someone advanced and/or wise, and pain/trouble/unhappiness. Which in combination then could have the meaning of a wise practitioner in magick who who destroys the root source of pain and unhappiness. Muniaka, Munyaka, Munka.
This is all theories only of course. I could be completely wrong here.
Another interesting thing to note is that "Munka" is Hungaryan for "Work" or "Job", borrowed from Serbo-Croatian "muka" meaning "trouble", as well as Slovakian "muka" and Russian "мука" which both mean “pain”. So theorically the "n" in the Hungaryan "Munka" could be interpreted as meaning "To get rid of trouble/pain", through "Work", which is the end-meaning of the word in Hungaryan.
Though, again, these are only theories.
