So the goons, I would say after just over a week and a half of hunting them for several hours a day and ignoring any of my uni work I have cracked the code.
They rotate maps 100%, they also only spawn at a certain time fraction on those maps globally, so for example; Goontracker was to report 7:45 (Your time zone) they were spotted on customs, they will have only spawned in raids that commenced at or extremely close to 7:45 on customs. The way in which I have discovered this information is that everytime I had found them on my pmc on the particular map rotation, someone else had reported a sighting at the exact commencement time as my raid, now you could say, well they could have been in your raid, but the rebuttle I have is, I was the only one fighting them on a few occassions + some of the sightings were during dead time period and also I play on a smaller region (OCE). Another way in which I had tested this theory after noticing this pattern I started to use my scav to hunt them; I know my particular scav spawn in times for certain maps for example; I spawn in with between 18-20 minutes left (most of the time) on Customs, Lighthouse and Woods, so I added 20 minutes from the reported time of the sighting then subtracted 1 minute (to make 19 minutes) to count for the map loading and matchmaking, this allows me to load into the raid that would have commenced at the reported period of time (TLDR; 19 minutes after the reported sighting I would queue up on the reported map obviously the time changes for other maps outside of those 3). Ever since I discovered this pattern and have used this method, outside of outlier scav spawn timers I have found the goons 100% of the time. With all this personal experience I can say other than non reported instances of the goons, they will always be in the raid that commenced at the reported sighting time and almost never outside of those periods (obviously there's outliers) but I only experienced this 2 times when they were on my map as my pmc where they did not receive a report on the website.