Hello my friend Pizman.
First of all thank you very much for your contribution for the tutorial.
HOWEVER!!!
1) " 1. The first Config ""ENG1 N2 offset no servo (condition)" is fine ! I woukd build it same way"
You said there is no problem with this. I want to add sth. You can ask why I choose corrected offset instead of normal. The reason is: It shows more correct values in PMDG aircraft, so it is more reliable.
2) "2. The Second Config "ENG1 N2 servo1" is unlogical or better unpracticable !
You say there: <<<<Apply comparison and if it is smaller than 30, set it to "1" else set it to "1">>>> This means If <30 then 1 else 1 .... in easy words "Always 1"
For this we not need to read a 8 Byte Float here.... We can read a FAKE Offset cause all we like to do is build a Config that campared always "1"
So read here Offset 0000 ( Automatic choosen if you do no entry yourself) . Also let Typ INt and Size 1 Byte as preselected.
Then Enable Transform and write 1 in the line..... This means that config is transformed to "1" at all time.
SURE the Precondition and Display( Servo) settings must be done again like in Özgürs Config."
You said here it is always 1. Why did I do this?
The reason is: According to my experience, if I use fake offset for this config which is always "1". And assign the servo to this config. When N2 goes beyond %30. Servo stays at 1. However, for a second it does an instant movement. I don't know why servo does this actually but I think It does this because when mobi looks at offset 0000 which is originally 0 but with transform"1", over 30 it looks at 64fc. During this instant change servo does a nonsense behaviour. Maybe, it is not a problem for you but it is a problem to hear this nonsense servo sound for a milisecond.

If you try, u will understand me better my friend. Thus, I didn't use fake offset and use "ENG1 N2 servo1" 0x2018 offset and my configs as I stated. Sorry but I don't agree with you when you stated "...unlogical or better unpracticable !". If you try my config and comparison Servo doesn't do that nonsense instant action which is more stable for me.
3)"3. The Third Config Is technical also already Ok..... whatever i would not use interpolation here
You say ..... <<<<Apply interpolation "0=1", "1=0", "2=0", "3=0".>>>> Means in easy words If value is "0" then set to "1" everytime else set to "0"
Same can be done with Compare : IF Value = 0 THEN "1" ELSE "0"
OR with transform line if($=0,1,0)
And sure also here the Precondition and Display settings are correct and needed as Özgür says."
The reason is: First I did this via comparison like u offer but somehow it didn't worked stable and I tried this way.
(EDIT: I changed my setup from interpolation to comparison like u said the nonsense servo movement occured again. I changed to interpolation nothing happened and it is more stable)
4) "NOTE: That System get one Disadvantage! The Servo is active in the "OFF" Position at all time after Engine Startup.
Özgür is right.... After a Engine shutdown the N2 decrease and servo resets ( Failure or manual shoutdown after landing) BUT Aslong engine is running the Servo "block" the Switch left from OFF Position!
If you did a mistake and turn the switch while flight to GND ( instead of CONT e.g. ) by mistake you will move the active servo against its direction and broke the Mechanic or Motor.
Thats why in "old" logic i try to build a system where servo is all time in "standby" position to get sure it could never "block"."
Sorry my friend but again I don't agree with you. In my design u can not make it GRD mistakenly. WHY? The servo moves and make the switch OFF However it stays where u can not make it GRD again. IT stops you if you want to turn it left to GRD again. You will say if you use mouse click what happens? Again it is not a problem. Servo goes to reset position it doesn't breake any mechanism like u said. Because the real switch in OFF position and it doesn't touch servo mechanism when it is OFF position. Look at the picture it shows finished servo action and make it GRD is impossible unless u shut the engines and servo resets...

However there are still chances to break the servo if you push with your full power when the motors running and you deliberately want to make it GRD.
5) I didn't use my system with placeholder and it can be another option as you said.
Finally...
I think you send your post with your experience and I bet you din't set your servos or PMDG and TRY.

As an old friend, I advice you TRY and SEE the results.
I only wanted to help the community, if you do not like my way, you can delete my post my friend.

However I used it in this way without any problem and also helped some friends I never met in real life but from this community. Do not misunderstand me, I know you want to help and you are the best and the most helpful person I have ever met. Just to be friend from the past I think you could ask me first before this post: Why did you do like this while there are other easy ways ??? But do not forget may be the nonsense behaviors of servo that I mention may happen only in my PC and sim. Your way may work without any problem in your PC/sim. As I said before, the configs in the tutorial I wrote was stable and used for a year without any problem.
See you my friend...