Music Work of a National Anthem Based on Someone Else's Work: Does the TOS Allow It?

Here's my scenario:

1. Song in focus is "Auferstanden aus Ruinen", a discontinued German national anthem since 1990 and now in public domain
2. I based my work on someone else's
3. I've made many modifications to distinguish my effort from my original base.

According to the Terms of Service (6.5), plagiarism is a violation of the terms; however, a lot of changes have been made from the originating piece that it won't look alike (instruments play specific notes instead of playing at all times, adding short sections not found in originating piece, etc.) and my work should not be identified at plagiarized.

And with that work, I plan on publishing it here. However, are there more guidelines to look out when basing my work on someone else's work on a public domain anthem (e.g., crediting the original author from where I base my work from)? I wish to share what I've done, and I want to make sure I don't find my self on the bad side of the terms.