Good question. We use SQL Server and Jet 4.
I may have confused Jet 3 at least once, in a repository I created to test the bug.
However in our production models the use of macronised characters is common, and it quickly becomes apparent when you cannot enter a macronised character (background - I use English (NZ) and M[ch257]ori keyboard where entering a character with a macron is as simple as pressing the "`" key followed by a vowel, viz "[ch363]").
Just to confirm, I fired up EA 1213 Corporate with a SQL Server (2008 R2) back end, Windows 7 Enterprise 64bit client.
I created a package, and entered m[ch257]cr[ch333]n[ch299]s[ch275]d words in every field I could. See the following image. The ext in blue
was not entered, it was pasted.

So while I may be the only person who has reported the bug, and it is difficult to recreate, I have consistently been able to repeat it across EA versions and for SQL Server and Jet4 repositories.
Note that in options under General "Use Jet 4.0" is set, this seems to be the only way to confirm that a Jet 4 Access database is being used.
And just for my own satisfaction I fired up a Jet 4 repository and exactly the same thing happened. It is not possible to enter from the keyboard a character such as "[ch333]" into the notes field (all other fields appear to work properly).