The letter contents were displayed properly in 1.3.10. I verified this during the beta when the option to revert to 1.3.10 was available. I suspect if you look at the name of the letter you're referring to and look it up on uesp.net, you'll find that its format will look something like:
In the name of Jarl
1.4.21 seems to have broken these dynamically assigned values which will assign a name of a person or location as well as a hold name associated with a particular hold in Skyrim. This issue was reported during the beta but like most of the confirmed issues that were reported, nothing was done about it for the 1.4 update.


