Timber frame? What is the external cladding? Do you have access to the drawings/ construction details?
I would be concerned if the ground was above the DPC, especially on a timber frame. If it were masonry bringing the ground level back to 150mm below DPC would clear up any problems as the masonry would dry out and there would be no long term effects. If the timber were to have started rotting, drying it out won’t undo it.
Having said that, if the foundations are good, nothing is irreperable. If there is any timber rot, after bringing the ground level down, it can most likely be sorted from the inside.