Hello Folks!
I now managed temperature plotting and wifi signal plotting.
All boiled down to creating a function that returns one value, namely a float or integer.
Mine did return also C for Celsius and db, which is not a number.
I created a function:
Name: w_mipsbe_temperature
Description: system temperature
Code: oid(“iso.org.dod.internet.private.enterprises.mikrotik.mikrotikExperimentalModule.mtXRouterOs.mtxrHealth.10.0”) / 10
Then I created two probes:
One for only plotting temperature)
Name: mipsbe_temperature
Type: Function
Available: 1
Error: “”
Value: oid(“iso.org.dod.internet.private.enterprises.mikrotik.mikrotikExperimentalModule.mtXRouterOs.mtxrHealth.10.0”) / 10
Unit: C
Rate: None
Comments, this is maybe not optimal, Available could be w_mipsbe_temperature(), but I never managed to get it working. It is a bit annoying when adding new devices, because the dude thinks it is available for the device and add it when you search for services to monitor.
The Value should be the function w_mipsbe_temperature(), but that did not work either by some reason.
The second probe is for alerting when temperature is above some level, here 19C)
Name: w_19_mipsbe_temperature
Type: Function
Available: mipsbe_temperature()
Error: if(mipsbe_temperature()<19, “”, “High TEMP”)
Value: oid(“iso.org.dod.internet.private.enterprises.mikrotik.mikrotikExperimentalModule.mtXRouterOs.mtxrHealth.10.0”) / 10
Unit: C
Rate: None
Comments, I did not manage to get the value from function I created, w_mipsbe_temperature()
Another oddity is that it does not seem to plot anything when the temperature is above 19, but it alerts as it should and plots correctly when temperature is within the limit 
Regarding plotting wireless links signal strength on client side, I faced some interesting issues, I had to create many probes (and functions) in order to pick up the client wifi interface, yet clients has only one.
Here is how probes were made)
Name: w_-70_snmp_wireless_link.5_db
Type: Function
Available: oid(“iso.org.dod.internet.private.enterprises.mikrotik.mikrotikExperimentalModule.mtXRouterOs.mtxrWireless.mtxrWlStatTable.mtxrWlStatEntry.mtxrWlStatStrength.5”)
Error: if(oid(“iso.org.dod.internet.private.enterprises.mikrotik.mikrotikExperimentalModule.mtXRouterOs.mtxrWireless.mtxrWlStatTable.mtxrWlStatEntry.mtxrWlStatStrength.5”)>-70, “”, “Signal LOW”)
Value: oid(“iso.org.dod.internet.private.enterprises.mikrotik.mikrotikExperimentalModule.mtXRouterOs.mtxrWireless.mtxrWlStatTable.mtxrWlStatEntry.mtxrWlStatStrength.5”)
Unit: db
Rate: None
Comments, I never managed to make any general function that returned a value, I got some parse error only or a straight line all the time.
The OID is different for exactly the same client devices, the part that differs is the last number, here 5. I had to make OID with numbers 2,3,4,5,6 and 7 so far. e.g different probes.
However it works, although clumsy and not the way I wanted it. When I attach and register new devices they correctly discover their probe.
Situation is also the same like for temperature, when value is below -70 nothing is plotted, but otherwise it works, it alerts and it plots nicely whilst above -70.
I will look more in detail on these functions to see if I can get some more nice working, not need to have the OID in the probes like above.
By the way, The new Dude now is very stable, we have had it running for a couple of weeks in a relatively large environment with some hundreds of devices. We use a CHR running with 4CPU and 4GB ram and 1GB disk beneath KVM in Centos and hpdl380g7 plus another hpdl380g8 p with ssd disks.
Anone who have some hints regarding those functions and probes ?