Dev will soon finish the new update of the other game, Lustful Spirit Hunt.
After that, the development of Hailey's Treasure Hunt will be resumed.
There's no ETA officially announced yet, but I personally speculate HTA next update might be released around late December, or earlier.
But there's a chance dev might have to go busy on other errands on the fourth quadrant of the year, since developing games is their part-time job. If dev have to work on other errands, then it might be released on next year's spring season in the northern hemisphere.