The lexical constraints on the EFL students' translation could appear at the level of morpheme, phase and clause. What are the best methods and procedures in describing these phenomena qualitatively?
The lexical equivallence is a very difficult undertaking and the morphological analysis is only a very small part of the factors dominating word meaning. The issue has rightly been addressed by writers like Baker and Pym. A translator's inginuity and awareness of the way words are employed by SL wrietrs is very essential. Evidently, Many words do not have a straightforward equivallence. For instance, non-core and subject specific lexical items carry deep associations whose understaning is a prerequisite to proper rendition. That is why Pym leaves a good part of the task to the translators for removing the impediments which make lexical translation a painstaking task.
I do agree with your statement that to find out the equivalence in lexical fields is a very difficult undertaking. Do you think this kind of constraints dealing with an individual's brain in processing second language/foreign language? Since, these constraints could be individual cases.
If I understand correctly, you basically want to analyze errors that students make while translating, and to what extent they are generalized or specific. If so, I would like to ask you if the students had access to any resources while they produced the text (I'm assuming it is written production, oral production would present different challenges), such as dictionaries, translation memories, etc. Also, were they constrained by time?
I ask these questions because one kind of error that you might be seeing is a "word choice" error, which tends to occur when students look words up in dictionaries and choose the wrong meaning.
In my opinion, word choice errors are specific to the student's L1.
Of course, we can't forget that a translation that is "too close" to the source text, to the point of containing unnatural constructions and overall not being very readable tends to be an indicator of lower proficiency, so what is the proficiency level of these students? How was that assessed?
Am I in the right direction, or was your question aiming at something different?