John C
No big secret... Flight phases are listed in FCOM 4.02.20 .. p11. (Always takes me ages to find that page....)
There is no phase called "initial climb".
Switching from TO phase to CLB happens automatically at ACC ALT, or by engagement of another vertical mode before reaching ACC ALT. Selection of TOGA following EFTO does not change the vertical mode so the flight phase remains TO.
In that situation you want to remain in NAV or HDG, and not change to GA TRK.
you could say you will not get GO around mode whilst still in the takeoff phase
True - if you need TOGA for some reason during a FLEX T/O you do not want G/A TRK to engage.