Yes understanding the vocabulary and jargon is extremely important, especially when translating texts.
I have to admit that in the year and a half since I have graduated I have focused on oral translation and have not yet tried my hand at translating texts, with the exception of some Vinaya outlines that weren't available in English and were required for a course Geshe Sonam was teaching.
From that limited experience it seems to me that oral and written translation require different sets of skills. Certainly written translation requires precision in terms of vocabulary and grammar that is not required as much in oral interpreting, except when dealing with the more technical topics. Also, one has more time to really polish the translation whereas in oral interpreting you are a bit on the spot. I try to stay as accurate to the Geshe's words as possible,while at the same time being aware of the meaning he is trying to convey.
I agree that translation can be very humbling. It is good for a poke at your self-cherishing. I have had both the geshe and the audience laugh at me at different points, and it is amazing how one gets used to it. I am now at the point where I even find such instances funny myself, rather than terrifying as I did in the beginning.
The role of "teacher" was never something I was never comfortable with as I am not able to embody the example of the teachings. So in this way translation is perfect for a flawed person like me to be able to contribute to the dharma in at least some way.
In order to ensure my mind never comes under the power of the self-cherishing attitude,
I must obtain control over my own mind.
Therefore, amongst all empowerments, the empowerment that gives me control over my mind is the best,
and I have received the most profound empowerment with this teaching.
brtsal ba'i bkhra drin