The "breath comma" is indeed on the symbols palette, as well in MTDL3, MTDL4, Encore 455 and Encore 502 (Windows versions at least). Right under the "segno" sign.
However, in M4/E5 the symbol shown on the palette is more like a dot, while in M3/E4 t looks like a comma.
Unfortunately, the created symbol in in both versions is quite too small, so that it looks like a dot at normal display sizes (but when zooming one can very well see that it's a comma)... So now the palette matches the reality, while I would have preferred that the reality would have matched the palette.
With Encore, I had created an "expression" which is a standard comma (font "Gill sans", bold, size 28) and fits my needs (and also a "little breath mark").
(I now found out that the expressions I created in E455 are not available in E5. Perhaps it is "normal" in a technical sense, but nevertheless the user with a lot of own expressions may find it quite a pity).
The flat, sharp and natural sign in the two palettes have different functions. These in the notes palettes are the regular accidentals, modifying the pitch and displayed left of the note. These in the Marks1 palette are drawn like other marks: when placed "on" a note head, they display above the note, and they don't alter the note. As far as I know, this is common in ancient music for reminder/courtesy accidental marks. Though I find them a little small to be useful.
André Baeck, (Belgian, now living in the south of France); also known as Andre_B
User of Encore 5 since March 2009 - Windows 7 (and XP)