Thanks a lot @Ramaniscence, I was not aware of the correct verbiage, and have corrected all references in the project (hopefully it is correct, please correct me if it is still wrong). MD5 checksum verification should not be too difficult to implement, so I will look into that. Using the alternative mirrors in a random order is also a reasonable idea, currently it only uses the mirrors if the first one fails.
Regarding the RSS Feed. I only use it for fetching the latest song number, then the script fetches each song page separately, since the URL format is fixed.
UPDATE:
I have now implemented MD5 checksum verification, and shuffled the order of used alternative mirrors to distribute load on servers. The new version is available on the site.