I could find no documentation on the specific "Alchemistgenerationtask" folders, but can offer a bit background information on the process photosanalysd and the "Containers" folder.
The folder hd/users/me/library/containers is containing caches that are used as a sandbox for the safe communication between apps and processes. This way a process can only access app data that the app allows the other app or process to access. In your case you are looking at the sandbox used by Photosanalysisd, a process that is analyzing all photos and videos in your Photos library, trying to recognize what the items are showing. Many tasks in Photos are depending on the results of photosanalysisd, so you should not try to interfere with this process. It will continually run in the background, whenever you import new photos.
I I have no idea what the fancy name for the folders is referring to, I have first seen these folders on macOS Sequoia. Perhaps the name has been inspired by the ambitious transmutation projects of the alchemists.
Previously I have only seen the name Alchemy in the frameworks used by the Music apps (GarageBand, MainStage, Logic Pro) for the synthesis of sounds.
The oldest AlchemisGenerationTask folder on my Mac is from June 2024. all older alchemy is related to music and sound synthesis.