Wicc didn't show much enthusiasm; he's just about to release a new pack of templates in the new HotA format, and he's thinking about making some long-overdue changes to it. Since the exact list of these changes is still being considered, he's not in a hurry with the SoD versions. But if there's a strong demand, he can speed things up.
1. Remove schemes with 3 cities from the template pool, as they result in a restart in 99% of games by mutual agreement.
2. Remove one of the two identical, overpowered schemes.
3. Fix the asymmetrical guard placement on one of the schemes (I don't remember which one, but I can clarify if necessary).
4. Add the XL+U format; there was even a text file with similar schemes.
Therefore, I don't know how to improve the balance on XL+U, except perhaps by creating a mirrored XL+U.
Of the old ideas, I remember only the thought of converting Diamond to XL+U; there were some difficulties, but I don't remember what they were.
Also, there was a long-standing idea to create a template that is more G+U or H+U (the next one after XL) or a separate version of Jeb G-U (H-U) with a larger number of cities in the starting and central zones.