Jane Stapleton makes a good point about the difficulty of doing comparative law in other languages here (pdf). Speaking of English-speaking lawyers and scholars who analyze foreign-language concepts or institutions, she asks:
[H]ow confident can a domestic practitioner or judge be that it is the output of these foreign lawyers that are put up for translation into English? This problem is especially acute in Code systems where certain academic commentaries on tort law both within and outside the Civil Code have influence and authority far beyond any academic materials in English-speaking jurisdictions.... The fact that, whereas the English legal tradition treats judges as the senior partners in law-making, the Continental tradition recognizes legal academics in this role, partly explains why some Continental jurists make statements that such and such is the “correct” “solution” to a legal issue. Such language can shock lawyers in common law jurisdictions where it is customary to couch normative arguments with greater reserve, unless they appreciate that these Continental lawyers seek to have their academic commentaries accepted as law. The legal cultural reasons for this difference in the role of jurists are fascinating in their own right, especially in comparison to U.S. and other common law systems. But the point I want to make here is that of the six or so most authoritative and extensive commentaries on the German Civil Code and extra-code law of obligations, none has been translated into English. This means that English speakers do not have these texts available so as to provide the necessary foils for the one extensive text on German tort law that has been written in English. Moreover, to my knowledge there are no other texts, written in English or in translation, that deal in detail with tort law in other foreign-language jurisdictions.