Currently Being ModeratedMay 4, 2012 9:58 AM (in response to wideEyedPupil)
The keys they chose definitely aren't very intuitive, but they are explained in the AppleScript Editor help - escape will accept the current completion, and as long as an ellipsis is next to the cursor there are multiple possibilities that can be shown by pressing option-escape (from there, a more normal up/down arrow and return select the choice).
The scripting dictionaries (if implemented at all) are entirely up to the developer, so the terms for any given application (or application version) will usually be different than those for another application, so you would need to check the dictionary by opening it in the Script Editor to see what the exact terms and their usage are.
Currently Being ModeratedMay 4, 2012 6:39 PM (in response to red_menace)
I found out that the F5 key accepts suggestion while looking at scripts on MacScripter. I later realised I needed to be looking in the Scripting Utliity Guide not the language guide as you said — thanks. Oh yeah F5 why didn't I think of that almost as logical as ESC key!