Okay, I have an answer for you. Nearly five years after your question
If you get this error message when importing the meta data from an Itunes xml file. I have run the iDateAdded 1.5 script for several different XML files I have output from Itunes playlists - one for each year of date added. Most of my XML files caused the script to fail with the "Chr" error, line 226 col 10.
So, all the Added dates for tracks were updated correctly until the error occurred each time, and I noticed the MM status bar shows which track has just been updated when the error occurs.
To workaround the problem:
Open your XML file, find the track that was displayed in the status bar, then "hide" the subsequent track - the one that has caused the script to terminate.
By "hide" I mean: delete the whole reference for that track including the <key> number and the entire <dict> section for the track.
A better workaround:
The filenames of the tracks that terminated the script always had non-english characters in them. Eg:
Я сошла с ума (I've lost my mind)
Нас не догонят (Not Gonna Get Us)
so the better workaround - change the filename of those tracks to exclude the non-english characters, then change the filenames of each in the xml file and re-run the script. That worked for me.
The best solution would be to modify the script so it works correcly on all charactersets. Good luck with that!