I’ll chime in saying that probably it is not needed to know which exact lengths are used by Pro Tools: you could simply loop strLength from 2 up to the length of the full name of the plug-in.
I hope Pro Tools will be smart enough to cope with the probably duplicated names that will be returned by getShortenedPluginName() for that range of values.
Disclaimer: it’s just an idea, I haven’t actually tested this or experience about this specific issue.