Offline herald spawning logic - test and observations

I'm a SSF player and in previous version spawning heralds on single player was quite hard compared to online. I was hoping new patch will change that, as Blizzard was promising that it will make it easier for solo players. But first 2-3h of playing were pretty dissapointing, it was not better than before, maybe even harder. I initially thought my game is bugged as I was not able to spawn any

Herald, I found few posts on reddit and some forums where people reported similar issues, but then I found first

Herald maybe after 2-2.5h. So I decided to look how they changed spawning chances compared to previous version.

Initially we had 2% chance to draw

Herald ire, then 1% chance co convert etc. Now configs look like this:
That looks like input for sigmoid function, I initially thought that it defines a chance to spawn based on area level and that function would look like that: So I created a dummy mod to check that. I Increased chance drastically but without effects. Even with 30% chance for 90 area level I was not able to spawn heralds.

Then I remembered that Blizzard said that chance to spawn

Herald will increase with every monster we kill in TZ. So I checked if that is not based on area level but on kill count in TZ. I modified my mod to give 0% chance untill 20, and then increase it to 30% at 30. I tested it by terrorizing A1 and clearing

Blood Moor one monster after another and it looked promising, I was not able to spawn

Herald before killing 25-30 monsters, and soon after hitting threshold of 30-35

Herald was spawning. But then I started testing it on other locations and results were different, I needed to kill 50-60, sometimes more monsters for

Herald to spawn. That means it was not kill-based, but somehow tied to killing monsters, as I was getting consistent number of kills per specific zone before

Herald spawn - the bigger the zone the bigger the number.

So right now my hypothesis is that spawn chance function is based on % of monsters in zone killed. That brings few questions:
1. If it is true does it mean that unless we will kill around 50% of monsters in area we won't be able to spawn

Herald (chance grows over 0% after 56%)? - So far I was unable to do so, heralds always spawned after clearing 70-100% of map, but maybe I was unlucky?
2. If we move to other area, what happens with our accumulated "clearing" - according to my tests it is counted separately for each area (or maybe TZ area group) - even if I cleared half of 3-4 maps, I had to clear almost whole 5th to spawn

Herald.
3. Can we spawn multiple heralds on same map? Again I was unable to, to spawn T2

Herald I always needed to clear 2nd area, but maybe I just did not test it enough (until now I cleared maybe 40-50 areas with different settings).

There is also a question of other property they added in 3.2 - "zone_completion_weight" - each TZ area has this property, it varies from 0.5, through 1.0, 2.0 up to 3.0, what may suggest that calculation for some areas may be different, but I also tested it by giving

Den of Evil different values (from 0.01 to 500.0) and was unable to find any relation between that value and chance to spawn

Herald.

Does anyone else did some tests on that? Or maybe knows something I missed?

I guess that most people play online, especially that early in season, and we know from last season that logic for online games and offline ones can differ. But if there are some SSF players - what are your experiences with heralds in 3.2 offline? Were you able to spawn

Herald right after entering some area or spawning multiple ones in one?