SMK suggested CharisSIL, which I've downloaded and tested with XEP; it looks good. I'll now try integrating that into FOP. I've also updated the Collator after discovering that we had not included barred lambda without a following apostrophe, causing one (actually erroneous) example of that to be sorted to the beginning, a mystifying thing for a while. I've made a little more progress with the rendering of entries, but I don't have a model to work from yet so it's just exploratory.