Many thanks for your patience, I am pleased to be able to continue assisting with your query now.
If someone is facing redundancy, you do have an obligation to make an offer of suitable alternative employment, if such opportunities actually exist. If none exist, which appears to have been the case here, you can offer him whatever else is available, which he can consider and potentially apply for, or reject it for being unsuitable and opt for redundancy instead. If you offered him something that was not suitable and he has rejected it and opted for redundancy, that is not constructive dismissal. He has exercised his right to reject it and is getting redundancy instead. Constructive dismissal would exist if you offered him an unsuitable alternative, he rejected it and you are then refusing to make him redundant.
The language issue is something you should have only considered if there was an obvious or likely disadvantage due to is language skills, or he had requested an adjustment to help him with it. If there were no obvious grounds on which to consider he needed assistance in that respect, you cannot realistically be accused of discrimination and he should have flagged this up earlier rather than just proceeding with it.
With the appeal, if he does not turn up just go ahead and do whatever you can without him and make it as far as possible, but he will not be doing himself any favours by refusing to attend.