Translating to the same language but different script
- IMO, this doesn't need separate wikis. Your suggestion may be used instead, or possibly other methods yet discussed.
- Yep, "Noto Sans Tagalog" is all configured and I can type and read Baybayin without Unicode boxes.
- I haven't tested it yet, however, I have plans to make a Baybayin version of Noli Me Tangere in Tagalog Wikibooks as I am an active contributor on that book.
- IMO, yes, we can develop that as well. I see minimal problems as it is just character/string substitution from Latin to Baybayin (ex. ka -> ᜃ; ngi -> ᜅᜒ; po -> ᜉᜓ;).
- As far as I know, no, there are none. Sad.
Yeah, that's the problem, there isn't an active Tagalog community these days. I think it is wiser to develop/program an automatic script to transliterate Tagalog Latin translations into Baybayin, and I could help with that.
Yoiu probably know that the Baybayin script is more "defective" than the modern Latin script which has more distinctions (even if some Latin letters are allophones in some, but not all Philippines languages, such as ra vs. "da (allophones only in Tagalog, but not in other languages that uses/used the Baybayin, and today even need the distinctions: the historic allophony of ra and "da is less effective today, when so many people have been exposed to English or historically also to Spanish and Dutch, and still today to other Chinese and Malaysian languages; and also need and use many borrowed proper names)
For what I see, the Baybayin alphabet (unfortunately encoded in Unicode and ISO 15924 under the normative but too restrive name "Tagalog") is simple to support with a transliterator from Latin (but care will be needed for the ba/ra distinction even if it is allophonic in Tagalog language for some people while it fact it shows today a clear contrast, the allophony being only marked by the contextual mutation depending on surrounding vowels): in the Baybayin alphabet, allophones may or may not share the same glyph, an in my optinion they should have been encoded separately (using a variant code where needed if we want to make or drop the visual distinction of "ra", with the letter "da" encoded always without the distinction: an Unicode font renderer could easily make the proper choice of glyph for "ra" automatically if the language is known: in Tagalog/Filipino language the distinction would be removed so "ra" would use the same glyph as "da"; this would also facilitate the bijective conversion with the Latin script in transliterators, so immediately the Philippine languages could automatically get a rendering in the Baybayin script without needing any development of a separate content).
As well there are only 3 vowels A/I/U in Baybayin, when Philippine languages in the Latin script also use E/O as historic allophones, which are also more clearly distinguished today. The same solution would ease porting, using variant selectors for each of the 2 Baybayin vowels I/O to preserve the distinction alreaday present in the Latin script.
Note that Unicode has left one empty cell in the Unicode block, it was not for the Tagalog language itself, but other Phillipine languages using the Baybayin alphabet.
Note finally that Baybayin has several graphical traditions (at least 8 are documented for different languages): only one tradition for the Tagalog language was studied in Unicode. The presence of an unallocated slot in the encoded script is a clear indication that this space was reserved, pending further studies, so that the Baybayin script is still not completely encoded and was only encoded for one form of the Tagalog language (hence its unfortunate name given in the Unicode/ISO 10646 encoded block, which is normative and cannot be changed, just like the code "Tglg"). The English and French names shown in ISO 15924 however should be clearly changed to Baybayin, they are not under a stability rule
I think you should discuss theses issues with Unicode and send requests, so that Baybayion can be used more easily and transliterators with Latin can work reliably, while still preserving the distinctions needed for other languages than just one of the historic forms of Tagalog (before the recent creation of its modern official Filipino variant).