Dear colleagues,
as I tried to express earlier, the statistics we have on language and writing are very imprecise. Estimations speak of ca. 6000-7000 languages globally. I couldn't find any scholarly estimates on how many languages globally have some written form using Roman/Latin script, however I could find a figure of 500 African languages (out of ca. 2000) having some written from, most of them using Roman/Latin script, and personally I don't find this figure to be unrealistic. No matter how we would try to estimate global figures on the basis of such areal ones, the number will be way too high for us to walk from language to language, which is why I would opt for going from codepoint to codepoint.
Regarding the schedules, I think one way to get some idea about the time required would be if we were to consider the size of our codepoint repertoire and then compare it e.g. to the size of the repertoire Arabic GP had to work with. However that would still not be overly realistic, since the accessibility of expertise and knowledge on these orthographies will have a much larger impact on the speed and quality of our analysis.
Anyhow I don't think it would be a problem to simply explain the facts and the difficulties within the proposal and then indicate that any current estimate is speculative for now. I hope this is helpful.
Best wishes,
Meikal