Started work on this zone.
Spawns (thrash)
From observations on Live they really seemed to spend a lot of time designing movement for spawns in this zone. So far I have been working on spawn locations in the tunnels and each spawn location seems to be able to spawn spawns (e.g. sewer slimes) with pre-set movement paths, but there seems to be several (read at least 5-10) set of pre-determined paths for each possible spawn.
For this run-through of the zone (and still keep my sanity intact and be able to finish within a reasonable time frame), I have decided that for single-spawn type spawn locations (e.g. locations where only sewer slimes can spawn) I collect three set of movement paths from live for each spawn and create scripts for that. That way a spawn location will have some variation.
Those are the easy spawn locations. Other places there can be up to 5 different types of spawn types for a single spawn location (in the corners of the tunnels there are usually two spawn locations and they each can have 5 different spawn types (e.g. slimes, hoppers, sludgewalkers, ratongas and rats). For these corners I collect two set of movement paths for each of the 5 spawn types and then I make two associated groups. That way I can have two of the same spawn types spawned at the same time (which is consistent with what I see on live), and there will be a fair amount of variation in movement paths. To all of that you can add that some spawns have two genders too...
While I work on corners I spawn all the required spawns for the two associated groups, so if you happen to tour the Ways these days and wonder why some locations have way too many spawns now, please don't remove them - I am working on movements and need all of the spawns done before I can create the associated groups.
Progress
I had a bit of time last week, but a lot of it was used learning about movement across grid lines (that one was REALLY annoying until Cynnar and Jabantiz taught me about it

, how to effectively work with the Movement parser (the JOY when I started using the delay command, that made location collecting so much easier not to mention faster), learning about spawn scripts in general, etc.
So far I am working on the first tunnel, and quite happy with the result. The aim is that if anyone goes through the zone they will not be able to distinguish Emu from live - even down to thrash mob movement patterns...
However:
The Ratonga jog
Ratonga walk animation was really odd and quite different from Live (at first I thought they were using the run animation by mistake). It turns out that Ratonga walk animations were changed by popular request in 2016 and therefore the diseased ratongas on the Emu look like they are jogging instead of walking. You get used to it after some time...
Link to forum thread about the ratonga walk animation upgrade