Relations are always localized and you cannot share a oneToOne relation with multiple locales. Each localized entry is a new entry in the database and in a oneToOne relation you cannot attach one-side to multiple entries. All locales of a content-type share the same database table but they are not the same entry. Localized entries basically have a hidden relationship between them but they are each independent of each other.
So the two options are either:
- Change the relationship type to something that would allow for the welcome message to be attached to multiple hotel entries (localized entities)
- Duplicate the welcome message and attach it to the localized entry.