There has been quiet around this topic so I'll try, please feel free to correct me if I'm wrong.
If I have understood correctly ranks 1,2,3,4 & 7 should have same pitch. Mustette 5 I'm not sure as my harmonium has only 4.5 ranks and it uses that stop also for Celeste and it is tuned +9 cents from 2 rank.
Celeste stops 5 Harpe Aeolienne, 6 Voix Celeste and 8 Äolsharfe 8' I have understood that in art harmoniums one rank is tuned lower and second is higher. For example -4.5 and +4.5 from 440Hz to get ~2Hz/2 beats per second undulating effect.
I tried to measure ranks 1 to 4 but reeds are so dirty and harmonium is overall out of tune that I cannot say 100% if there is offset in rank 4.
Then pressure affects also to tuning and should kept at same level when tuned or measured.
I don't have art harmonium where to verify this hopefully one day I would have also one here..... still on process
I might be totally wrong so someone who knows this please correct me I'm also interested to know this. Also what pressure you're using when tuning would be interesting to know.
Or if someone has accurate tuner at home beside art harmonium maybe he or she could do some study.
But that I can say that tuning of Celestes is quite time consuming specially if you want to keep steady beats all across keyboard. And after tuning of harmonium you don't need to go to gym as you have lifted action up and down for several times.
Best Regards Jaakko
PS. If you have questions about tuning of reed organs those I can answer right away.