I'm sorry--you did say at the beginning that you are working in UEB. The question you have raised is now a gray area in the rules, but I do have a strong recommendation to offer.
What we have here is English text with foreign language words used within it. These foreign words are considered to be in an English context.
First, please refer to Braille Formats 2011 section 1.15. Briefly, that is the current practice. It says that foreign words in English context are contracted (except for accented letters, which thankfully does not apply here. There are no accented or Greek letters.) It is the NBA recommendation that this practice be continued at this time. In this case, use contractions and retain the typeforms as in print. If I understand correctly that you are doing this in UEB, use the UEB indicators for the typeforms.
I know this appears to conflict with UEB section 13 that states no contractions are to be used in foreign words. Please read that section carefully and see Section 13.2.1. It says not to use contractions in foreign words, even in the English context. Be sure to see the note that follows. Note: It is permissible to disregard this rule provided that there are appropriate braille authority policies and guidelines in place which transcribers in your country are expected to follow to ensure that ambiguity is avoided.
The BANA Braille Formats Technical Committee is working with BANA to align Braille Formats with UEB. Until final approval for this update occurs, current practices continue, and the use of contractions is the current practice. The BANA technical committee has recommended that the note in 13.2.1 be incorporated into Braille Formats so that the current practice of contractions usage continues. Therefore, at this time, the recommendation here is to continue using contractions in the foreign words that you have asked about here.