But Elizabeth had now recollected herself, and making a strong effort for it, was able to assure with tolerable firmness that the prospect of their relationship was highly grateful to her, and that she wished her all imaginable happiness.
This seemed very wrong to me, but my dictionary tells me "grateful" has in the past be used for "welcome".
grateful | ˈɡreɪtfʊl, ˈɡreɪtf(ə)l |
feeling or showing an appreciation for something done or received: I'm grateful to you for all your help | she gave him a grateful smile.
• archaic received or experienced with gratitude; welcome: the grateful shade.
mid 16th century: from obsolete grate ‘pleasing, thankful’ (from Latin gratus) + -ful.