I want a specific symbol to change its shape when it’s at the start of a word. I know that that can be made with chained context substitution, but it’s not working for some reason.
Did you connect the chaining context lookup to a feature which belongs to the correct Script?
Yes, and it’s working now. I forgot to update this thread. However, I have another issue. Letters in this script have below-base forms, as well as “host” forms under which the blwf forms attach, but I have no idea how to prevent the host base from turning into a diacritic when I enable blwf.