I've had mixed success with seedlings - I've tried 3 flasks twice, first time round things went really well and I'm pleased to say I have lots of baby Cattleyas, second time not so well, out of about 25 seedlings only about 5 are still going. I think the second time where I went wrong is I left them too long to acclimatise with the lid of the jar slightly open. I used the guidance on this site and it seemed pretty good
Deflasking
If you think it would help I can post a photo of the 2 small propagators that I'm using for the seedlings.