Exactly how do you come up with this? Do you own these products? Are these products sounding a musical pitch and you are checking them against a tuner? If this is true it appears to me a lot of programmer analysts need to come out into the real world. The programmer's programming the tuners all got it correct.
Hi again, John.
Google helped me find the information. I typed in manufacturers and looked at how they defined middle C. That's what led me to links like the below...
https://discuss.cakewalk.com/index.php?/topic/2464-why-does-cakewalk-call-middle-c-c5/https://vi-control.net/community/threads/is-middle-c-c3-or-c4.53035/https://www.logicprohelp.com/forum/viewtopic.php?t=91282https://goldmidi.com/community/resources/middle-c-in-fl-studio.59/and so on...
As you've already mentioned, the most important thing common to all is that middle c is note 60 and then multiples of 12 will take one up/down octaves. That does not change.
e.g. note numbers: 60 (mid C), 72 (up octave), 48 (down octave), etc.
Regards,
Noel