As I hear them used in Dar es Salaam, 'kufahamu' is more like "to be familiar," while 'kujulisha' is like "to inform." But I also hear plenty of interchange, though much of that seems proportionate to the speaker's education level.
*I will inform him/her
"Nitamfahamisha" really translates to 'I will notify him or her.'
Is responding, "I will inform him" too far from being correct?