Javanese contrasts slack and stiff voiced bilabial, dental, retroflex, and velar stops.
See Voiced velar stop for a possible reason.
The representation of the voiceless velar stop.
The voiceless velar stop or voiceless velar plosive is a type of consonantal sound used in many spoken languages.
Features of the voiceless velar stop:
It can also occur when the syllable margin is a velar stop or nasal, or a liquid.
Retroflex stops are less common than velar stops or alveolar stops, and do not occur in English.
The velar stops (viz.
(See voiced velar stop for another such gap.)
Thus g here does not indicate a voiced velar stop but rather a voiced velar fricative, similar to luego in Spanish.