Again, Cae, this is really helpful. I think Draigcoch, Blodynbach and I will be looking very closely at the chapel records when we next visit Holyhead (me, hopefully, in May or thereabouts). However, Blodynbach lives very near Holyhead so may be able to get there sooner.
Something of interest I've just uncovered: the present Capel Bethel was founded in 1895 which is a bit late for the interment of Jonathan Burnal in 1875. Do you happen to know if there an earlier chapel of the same name on the site?
Amlodhi