I was hoping that someone with better resources on Aztec mythology would speak up, but in absence of that, I'll tell you what I found looking into this online. Chief among it was that I could find nothing whatsoever backing up that interpretation of the five flowers, and lots saying it meant completely different things. Given that, my suspicion is that this is a misinterpretation of the source material on someone's part. If not yours, then the article authors' (or perhaps their source's).
Xochipilli is associated with both the Seven-flower (Chicomexōchitl) and Five-flower (Macuilxōchitl). The "Five" variant appears to be part of a series (of yes 5) of 5-named deities that are all associated with excess or pleasure. Sort of an Aztec analog to Christian culture's Seven Deadly Sins. The fives are Five-vulture, Five-lizard, Five-rabbit, Five-grass, and Five-flower. Five-flower in particular was associated with gambling and music.
The Aztecs did have a belief that there had been 5 Suns (taken literally, or "worlds" less literally), but they didn't think all existed simultaneously. Rather that the world had ended 4 times previously, and it was their sacred duty to prevent it happening a 5th time. There is no indication I can find that they believed there were currently other worlds out there.
Azetcs were also not a particularly maritime people. In fact their empire had noticeably little coastline, considering where it was, and their capital was about as far inland as you can get in Mesoamerica. Most of the archeologists specializing in their larger Nahua culture will tell you it likely originated in the Southwest American deserts to the north.
Aztec Empire in 1519
So I'm not finding much support for the idea that they had any concept of whole other continents existing beyond their eastern and/or western sea, and given their cultural roots and outlook, it seems highly unlikely.