That’s very interesting, thanks for this entire thread. In fact I had requested an open and editable system with the possibility of multiple variations per phrase, and it seems it’s been there right from the beginning and I did not know about it. Miracles do happen! 
I’d like to add some more insight on the topic being much less US-centric, as I fly in Europe I can confirm there are tons of difference in phraseology, beginning right there at the startup request. I won’t go through everything as detailed as you did, but just add a little information here and there.
Here, the initial call is never “ready to copy”, “ready for clearance” or anything like that. The correct way is to give the ATIS (again, not with stuff like " on board"), but rather:
- “Airline 123, information [atis], request startup”.
That’s it. This will trigger activation of your flight plan and the most basic clearance you could expect (and that is mostly given) will be:
- “Airline 123, startup approved, cleared to [destination], [SID] departure, squawk 4321”.
Again, that’s it. Simple as that. No climb to, expect anything or other stuff. The climb clearance is part of the SID here. It’s that simple. Other instructions are optional and happen rarely if at all, and I wouldn’t expect them to be modelled (“reach 5000 feet latest 17 miles after departure end of runway due to glider activity…” you get the point).
If there is no seperate clearance delivery, you’d request startup from ground. Again, if there is none, then from tower. Otherwise you’d continue with pushback on apron or ground. As explained above, apron seems to be the “ramp” equivalent, if it’s controlled by some airport company and not actual ATC controllers (which ground control is):
- “Airport Apron/Ground, Airline 123, request pushback.”
- "Airline 123, pushback approved facing [N/E/S/W].
Next thing is taxi, and the only ones I hear on the freq just calling for “taxi” or “taxi please” are usually Americans. Otherwise it would be:
- “Airline 123, request taxi.”
- “Airline 123, taxi to holding point runway 21L via A, B, C. Cross runway 21R.”
If you were calculating takeoff performance for an intersection less than full length, this would be a good time to tell the controller for his planning: “Request taxi, able B/able for intersection B/ …”.
As you can see, there is a lot less “ready” and a lot more “request” in the phraseology here.
Stuff that could happen on tower frequency:
- “Airline 123, ready for depature.”
Conditional clearances are possible and always begin and end with “behind”, like:
- “Airline 123, behind next landing A320 on short final line up and wait runway 21L behind.”
Or if you were to depart via an intersection less than full length:
- “Airline 123, in B line up and wait runway 21L.”
The most basic takeoff and landing clearances have exactly this format:
- “Airline 123, wind 240 degrees 8 knots, runway 21L, cleared for takeoff.”
Checking in with departure, or in fact, any radar controller except directors, would include altitude passing and cleared altitude.
- “Apple Radar, Airline 123, passing [altitude_passing], climbing [cleared_altitude].”
- “Airline 123, Apple Radar, radar contact (or “identified”). Climb [new_cleared_altitude].”
As discussed above, I personally find the “and maintain” totally pointless, especially since many do this enroute all the time. If you are cleared for a procedure you are expected to follow the restrictions. If the SID contains restrictions, those might be cancelled like:
- “Airline 123, climb unrestricted [new_cleared_level].” or
- “Airline 123, open climb [new_cleared_altitude].”
The correct phrase is actually “cancel level restrictions” if I’m not mistaken but I’ve never heard that one IIRC.
Again, if a STAR has a given profile and you were to descend adhering to the restrictions, there is a phrase
- “Airline 123, descend via the [cleared_star] arrival to [new_cleared_altitude].”
Again, this rarely every happens here. Controllers like to assign levels themselves and that’s what they do most of the time.
Some more useless stuff I hear all the time is when I check in like „Some Radar, Airline 123, FL390“ they’d say „Airline 123, Some Radar, identified, maintain FL390.“ Well, what else do they think would I do.
Typical approach clearances would be like:
- “Airline 123, turn left heading 240, descent to 4000 feet, cleared ILS runway 21L.”
In some contries the controllers add other unnecessary stuff like “final vector” etc.
Landing clearance is exactly like takeoff as explained above:
- “Airline 123, wind 180 degrees 15 knots gusting 25, runway 21L, cleared to land.”
I’m not saying all of this is exactly according to standard X or Y. It’s some of the “more correct” stuff you would typically hear on the radio, and tons of variations not included.
Thanks to the hints above I started editing the file (forgot to backup the original, of course…) and if anyone would be interested in a more Europe-biased version, let me know. I’m not exactly sure if all details can be incorporated as they should though. For my very personal realism I’m trying to add lots of variations that might not be 100% correct but commonly used.
Editing the other than English files should be a way bigger task… Those translations were unusable in the past, not we have the possibility to edit them at least.
Other than that, I found a bug in the original file, search for “BEECHCRAFT” and there is the .text line missing, only the .tts line seems to be there by default. Should anyone care.