Yeah, your prediction does make sense:
Every month they are reducing both the interview pending count and the number of documentarily qualified backlog.
September/23: 275,506 pending interview / 314,853 documentarily completed
April/23: 370,125 pending interview / 409,021 documentarily completed
January/23: 386,787 pending interview / 422,954 documentarily completed
August/22: 388,780 pending interview / 421,668 documentarily completed
April/22: 421,358 pending interview / 453,797 documentarily completed
January/22: 439,373 pending interview / 465,978 documentarily completed
Clearly, the speed in 2023 has been faster than in 2022.
As you mentioned, the average number of interviews in recent months stands at around 40k monthly.
There's a noteworthy point in the report: This suggests that 60k is viewed as a "healthy" backlog, which is what they aim to achieve.
"Note: In Calendar Year 2019, on average, 60,866 applicants were pending the scheduling of an interview each month."
Thus, if they maintain the current pace, it would take approximately 5 months to reach this "healthy" backlog level (so around Feb/Mar 2024).
It's worth noting that since there's no category-specific breakdown, we can take this as a worst-case scenario prediction.