Meeting people where they are at is helpful. Just asking her how she is doing, acknowledging the posts possibly, asking her what she needs, or what might be helpful is encouraging. Offering a listening ear and prayers are comforting. I have one example, in particular, when my husband and I were at a workshop, getting help, and someone asked me a bit about our story. I walked away feeling terrible. I was having a “good” day and she proceeded to respond in a way that was not helpful. She responded in a very dramatic way and was saying things like that must have been like a knife in my stomach etc.
If you are concerned about your sister in Christ and her spiritual well-being, maybe you want to ask or say more, but I would try to build a trusting loving relationship with her, too.