When using the spell magic jar, what effects will follow the possessing wizard around from body-to-body vs. only affecting the host body? Some spells are easy to consider, such as bull's strength. But what about mental effects such as owl's wisdom, or even mind-altering such as charm person? Consider how any buffs cast on the host while it is possessed are affected by a casting of dispel magic. Also affected by this question is the consideration of a possessing creature still being affected by buffs cast on it before casting the spell (or are those spells simply wasting duration on its suspended-animation body?).
This simply isn't answered by the rules. Admittedly, it's hard to prove a negative, but here's what I've got:
The general rules on spell effect interactions are found here, and there's nothing in them that specifies whether ongoing spell effects follow the body, the soul, or both. This isn't surprising. Magic jar is more or less unique. The separation of body and soul it causes isn't a common enough situation to warrant being covered in the general rules.
For that reason, if there were rules that governed the unique rules interactions caused by magic jar, I'd expect them to be specific to that spell, and therefore included in that spell's spell description. As you've observed, the spell description does not include such rules.
Think of this as an opportunity for your GM to get creative. You could write an entire campaign based around discovering and exploiting the more subtle and undocumented details of spells, if you wanted...