You should know, I'm no expert - so hopefully someone can chime in if what I tell you is erroneous.
The first thing I would suggest is you make a new script from copy (which I guess you have done), but give it a different name, for example, SynthScriptDisabled and make sure that the first line is scn SynthScriptDisabled.
At the moment, your synth turns into E-DE because you haven't tailored the script to the synth. It's not as simple as just copy and paste in all cases. Basically, using the Damage Ed-E script as an example, you need to create scripts that point to custom synth and not Ed-E. A lot of the script is superfluous for what you're wanting to do. You don't want any references to Ed-E in there at all or it will affect Ed-E instead. I imagined the script would be a more simplistic - on par with most follower mod scripts, but there's a lot of stuff in there that I'm not sure about... timers, etc. The script also references a lot of 'showMessage xxx' and you'll find those messages in the GECK. You shouldn't use them for the Synth, though. You should make your own. If I was to do this myself, I would see if I can find all of those messages and references in GECK, look at them and then possibly copy them too, rename them and change everything up to reference the new stuff.
I can't really be much help here, I'm afraid. Sorry.
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