I do not think it is the OS, it might be the selected Language that does it, or the Version of Java, or the Forge Version, which in my case is English with Oracle Java 8 and Forge 1614. (despite being a German I can understand English better XD)
On the Loading Screen it cannot be properly shows as that one strips the § Sign out of the String without removing the 6, in other things it shows ?6 because the Minecraft Font does not have the § sign in it (since they use that for formatting).
I would like to see a Screenshot of where it actually works properly, since I did not see it so far.
Oh and I do not use WAILA so that might be my Issue. XD