Any Transmutation that results in a Legendary (cannot be bought or found off enemies ie: Turnip) cannot be extracted into a .dat, it will always give you a rare file.
It is by no means professional and I am not the best with google spreadsheets but I will clean it up sometime this week and post it. I'll be slowly adding to it. Right now I'm at 313/484(roughly 64%) of just Head/Body Linear Channel Ritual. I've been experimenting with Extraction as well, trying to find the hard percentages of Sync Stats and Item Extraction. You have no idea how much time you saved me, so I really do thank you Dataerase. I think I did close to 50 Turnip Extractions and was wondering if I was just extremely unlucky. Not uncommon for me as my drop rates on Monster Hunter games is horrid.
Now that I know Legendaries are not able to become .dats that makes experimenting with them quite interesting. I'm curious to see if they are only good for Extraction or if some really interesting Synch alchemy stats can be found.
If it helps to know for time sake, most synergies are material to material and don't require being on a specific bodypart/channel (except in the case of 3 material and 5 material synergies that transmute the center (body).) All the two material syngeries that work on head/body should work on leg/body or arm/body as well (unless theres a bug which some players have reported for the advanced rituals, i will eventually get to these). Of course, if you're recording all the channel edgecases with energy production as well then it's more complicated.
If you want to email me the chart before sharing it with folks feel free and I can tell you if anything on it is wrong or if you're missing an extraction on anything.