Likely a modern elaboration related to Greek xenia, meaning hospitality or welcome to a guest.
Xilenia appears to be a modern invention built on ancient Greek foundations, most plausibly constructed from xenos (ξένος), the Greek word for "stranger," "guest," or "foreigner" — the root of Xenia, the ancient Greek concept of guest-friendship that was one of the most sacred obligations in Hellenic society. In Homeric culture, xenia demanded that hosts offer strangers food, shelter, and protection, and that guests show gratitude and respect in return; violations of xenia were understood as affronts to Zeus Xenios himself. The name Xenia derives from this same root and has been a given name in Greek and Slavic cultures for centuries.
The elaboration into Xilenia — adding the -il- infix and the four-syllable flow — transforms the compact Xenia into something more ornate and distinctly modern. It shares a family resemblance with names like Selenia (from Selene, the moon goddess), Valenia, and other feminines ending in the melodious -enia or -inia. The X initial, while standard in ancient Greek transliterations, gives the name an exotic visual quality in English that sets it apart immediately.
Xilenia sits in an interesting position in contemporary naming: it sounds as though it might have a long history, its classical Greek undertones lending it an air of antiquity, yet it appears to be a genuinely new creation — a name that feels like it belongs to mythology without actually appearing there. For parents drawn to names that sound both discovered and invented, both old and entirely fresh, Xilenia offers a distinctive and euphonious choice with roots deep enough to hold.