Harry, you said you have seen printed editions with the Vedic signs, is that something you can easily share or refer to for me to find in a library?
I was quoting from an email conversation I had a while ago with a devanagari font designer so I don't recall the exact editions I was referring to. I think they were of the vājasaneyi-saṁhitā . But if you look at this edition of the vājasaneyi-saṁhitā, it will have at least some of these vedic signs, showing combination with the bindu. https://ia801604.us.archive.org/5/items/in.ernet.dli.2015.292661/2015.292661.Vajasaneyi-samhita.pdf (see page 6 etc.)
What about these signs:
Should they also take anusvara/candrabindu? They all seem to already contain a dot.
I don't know these vedic signs, but from the names these appear to be different forms of the anusvara, so I suspect they don't combine with another bindu or candrabindu .
One other thing to note. The rendering problem with MSWord I noted, i.e. the dotted circle put in when a character from the devanagari extensions or vedic extensions block is combined with an accent, doesn't occur with the Adishila font family. This is because there is a work-around you can put in a font (which is you put a zero width character at the unicode location where the dotted circle should be, so that whenever MSWord (or other software) tries to print a dotted circle it prints nothing instead.
Harry Spier