tDCS does not differ much than rTMS .. the laws of physics is just the difference either electric electric or electromagnetic electric ..
In removed lesions there is always a bone defect which may shift the waves whether electric waves/current in case of tDCS or magnetic ones in case of rTMS through the defective bone and directly to the brain tissue causing direct effect which does not just stop along heating.
And this will break the rule through which the DCS or TMS work by (transcranial) to be (intracranial) if this word suited enough.
So I think it is forbidden or at least hazardous to do sessions on top of bone defect.
And here is a link for an article discussing this .. they reached that it is questionable ..
Safety comes first because these non invasive techinques are actually not non invasive.