Bringing it down to individuals doesn't change the underlying math. Changing the premises would require a source of elemental attack, such as from a temporary buff or elemental advantage. But if you have +130% attack and elemental advantage, none of this matters anyway, because if a maxed team with elemental advantage can't beat the content, then no one can. The point of optimization is usually to overcome worst-case scenarios (otherwise you'd be better off running easier content you could clear more reliably). Lilims introduce risk rather than mitigate it, which makes them a particularly poor choice.
The final nail in the coffin for Lilims is that Lilims are useless to anyone running a team with 4-5 same-element characters. That means that Lilim users will end up ostracized with only other Lilim-users available as friends. From a game theory standpoint, Lilims are doomed to fail.