"Whispers of the Past" tranlsation LHYSS-EN-GWANWEN

Greetings, my fellow Tolkien language fans. I am very new to Sindarin and am working on some chapter titles in Sindarin. I have gone through the basic grammar rules multiple times and have it somewhat figured out. I came up with LHYSS-EN-GWANWEN. Here is my reasoning. Whispers (Noun) (Subject) (loss noun “whisper” becomes Lhyss according to the rules of final i-affection, a final 'o' would change to 'y' when the noun goes from singular to plural because the words of (preposition) and the (definite article) are (en preposition. “of the”) in Sindarin and cause the word Past (Noun) (Object) (qwanwen noun “departed”) gwanwen to stay the same. Am I on the write track?

You're on the right track. Only issue here is that gwanwen is an adjective (and also means "past" in the sense of "departed" or "lost," in case that's not what you intend), and in the phrase "whispers of the past," "past" is a noun, not an adjective. The noun form of "past" is gwanwas, so the translation would be lhyss en gwanwas instead. Alternatively, if you like the word gwanwen, you could rephrase the translation as "past whispers" and use gwanwen, forming lhyss 'wenwin.

Thank you Gwilithiel I totally missed that gwanwen was an adjective and that gwanwas was a noun.