https://www.youtube.com/watch?v=NQN9bnv-9wU
if any of you want some Good Stuff about their backstory; I definitely agree that Silence's anger is at least partially due to Saria's departure. Silence aims to cure Oripathy, and she's very clear about that in her promotion and trust lines. Whether her goal changed somewhere along the way to Rhodes Island or not, she's doing her best for Ifrit's sake. But. Just because Silence was in charge of a project doesn't mean she was doing everything from her own research and ideas. It's likely that Rhine Lab manipulated a lot of the project and put it under the guise of treating Oripathy. After all, there are comments from other characters (if i remember correctly) that say that Rhine Lab is quite sketchy.
Silence may take the blame for having physically carried out those orders, but she definitely doesn't seem to actively want to put Ifrit in the same situation. Ifrit is said to be improving, even. Her final file doesn't mention who sent the letter to the doctor, but I'd like to think it echoes the thoughts of both Silence and Saria - that Ifrit is looking happier than she's ever been, and she shouldn't be given up on. That Ifrit deserves to be more than what she was in Rhine Lab. These three better have the heart-wrenching story they're set up to have :(