Welcome to the community.
I understand what you’re saying, but please note I don’t fully know your entire setup, so I’ll base this on what I do see… sorry if I am wrong.
It looks like you have one HRV (Heat Recovery Ventilation system) that is controlled by five separate automations. I’ll address your points 1 and 2 below. Again, this is based on what I can interpret from your setup.
HRV Control - One Automation Instead of Five
Can you use just one automation to control the HRV, and group your Derivative Sensors and or your Humidity Sensors?
My thinking is:
One fan (HRV) = One automation, rather than One fan (HRV) = Five automations, which could lead to conflicts or overlapping triggers.
You can do this by creating sensor groups to remove conflicts:
- Go to:
Settings > Devices & Services > Helpers > Create Helper > Group > Sensor Group - Give it a name like: HRV Humidity Group
- Under Members, add all your humidity sensors.
- For Type, choose:
- Most recently updated if you’re triggering based on the latest change (This is the one I think you may need), or
- Maximum if you’re comparing peak humidity values.
If you decide to try this, I suggest disabling your 5 existing automations (don’t delete them just yet), then create and test a single new automation using the grouped sensor. I think this could simplify things, help avoid conflicts and achieve what your after.
If you have different maximum humidity thresholds for different sensors, it’s still possible, it just gets a bit more complex and will require a template sensors.
You can create a template sensor that evaluates logic like:
- If Sensor A humidity is ≥ 80%, then set output to 90.1
- If Sensor B humidity is ≥ 75%, then also set output to 90.1
Then, group these template sensors into a sensor group, and in your automation, simply trigger when that group goes above 90%.
This approach allows you to centralize your humidity logic and still use a single automation, even with varying thresholds for different sensors.
Just a heads-up, I’m doing this without testing, and these ideas are coming to me as I go. So if something doesn’t work as expected, please don’t be too hard on me! 
Notifications & Trigger Tracking
Use my 
State Notifications & Actions blueprint.
You can continue to use whatever you’re using now to trigger the automation (I think it is your humidity sensors), but have one notification automation instead of multiple. The blueprint allows you to detect which trigger caused it, so you only need a single automation. If you have different maximum humidity thresholds then you will need multiple automations.
Check out this helpful FAQ for more info:
Click here
Let us know how you go.
Blacky 