It makes me really happy that our game affected you enough to make you look into it that much!
To be completely honest, our main focus was on the flowers' colors, and that their names at least remotely sound like human names. The cool thing about flower meanings are is that they can be interpreted in multiple ways! So even if they weren't our main objective, we still made them work somehow:
Lycoris flowers are frequently used at funerals and are connected to various tragic legends. This is a nod at the fact that he was most affected by Lilium's death, and had the biggest inner turmoil when it came to figuring out how to help him.
(Yellow) Oleander's high toxicity represents his aggressive/proactive approach when it comes to helping Lilium, and the fact that he seems like the least friendly one out of the three. (It is, however, not meant to rate his approach as more or less valid. One of the main morals of the story is that there isn't "one right thing to do".)
Strelitzia is probably the prettiest and most extravagant out of the three, and so is the flower. Other than that we didn't think much deeper. :'D
Lilies are also frequently used at funerals and symbolically represent innocence. "Innocence" may be used in a more negative sense to signify "naivety" or "cowardice", which are probably Lilium's greatest flaws.
But of course all of this doesn't mean your interpretations were wrong! Technically, their meanings are whatever resonates with you most.
Thank YOU for your kind words, and I look forward to hearing what you think of Artificial Selection once you complete the demo!