“Undo” not working for script, gothic, and double-struck letter forms?

Has anyone else experienced anomalous behavior using "Undo" (Ctrl-z) with notational alphabet letter forms?

Since Mathematica's built-in functions are capitalized, one generally avoids beginning user-defined symbols with a capital letter, but once in awhile I define a symbol that includes a proper name and I want to preserve the distinction of the capitalization, e.g. Ry (Rydberg constant). My general solution is to use a capital from the alternate letter forms, e.g. \[ScriptR]y.

Anyway, I've notice that sometimes making and then reversing edits to single letters, or mixing letter forms using the rapid entry (Esc scR Esc) results in no action, but the undo list seems to be affected ("undo" menu option is grayed out indicating no more actions to undo).

In other instances, a number of characters are deleted on the undo action (instead of reverting to the previous text).

I've tested with the long-forms (e.g. \[ScriptCapitalR]) and I see the same behavior.

Are these alternative letter forms supported/implemented in "Undo" or is this expected?