The Warforged Resilience racial trait (WGtE, p. 68) states:
You have advantage on saving throws against being poisoned, and you have resistance to poison damage.
If an attack deals poison damage and includes a saving throw to avoid half damage, but does not inflict the poisoned condition either way, do Warforged have advantage on the saving throw?
For example, the spider's bite and the cloudkill spell would be examples of the type of save I am concerned about.
Best Answer
Against the Poisoned condition, yes; against Poison damage, no
You're correct about the particulars of the wording of the Warforged Resilience feature: because of the precise manner in which it is worded, you would gain advantage on Saving Throws against any feature that afflicts the Poisoned condition, but not against Saving Throws against any feature that merely deals Poison damage without actually threatening their targets with being poisoned.
Wayfinder's Guide to Eberron is still considered "Playtest" material
Although holding a higher degree of legitimacy than Playtest material usually gets (compare to Unearthed Arcana), the official stance of Wizards of the Coast is that the Wayfinder's Guide to Eberron book is playtest material, and that this won't change until it is officially released. This is supported by the fact that it's considered ineligible for use in Adventurer's League games (unless they are specifically set in the Adventurer's League Eberron Campaign Setting). A disclaimer in the Introduction of the book also confirms its non-official status:
As a result, there's still a chance that this feature will get changed before release.
So while your RAW interpretation of this feature appears to be correct, be aware that this could be an oversight or mistake in the wording of the feature, and that the intent of the feature is to protect against poison of all kinds, like with the Dwarven equivalent feature.