cum gravi ... calamitate:
An ablative of manner with tamen separating the adjective-noun pair.
AblMan
per ... Sullam consulem:
Remember that Eutropius has a tendency to use per plus an accusative to express agency in the
same way that passive verbs typically use ab plus an ablative. Translate as "through the actions of"
or "by."
cum ... egisset:
Remember that egisset is the perfect subjunctive of ago, which, when paired
with bellum, idiomatically means "to wage war." CumCircum
in eodem bello:
Forms of is, ea, id can be compounded with the suffix -dem
to mean "the same."
Isdem
praetor:
Praetors were government officials, second only to consuls, who served as judges. See here.