This just means that you can't appeal a factual finding, you can only appeal an interpretation of the law. Picking out what is relevant (a) requires a proper review of the decision which you are appealing and (b) constitutes legal advice - so you're not going to be able to get your answer here.
Your best option is to engage a lawyer who can do this for you. Your appeal pathway appears to be to the Supreme Court, so it's not something you want to get wrong.
The DIY option is to:
1. Identify the issues you wish to appeal (which you appear to have done above);
2. Look at the explanation given in the decision for the findings you wish to appeal;
3. Determine whether those findings are made on the basis of a finding of fact, or an interpretation of the law;
4. If it's the latter, then that is a question of law and you phrase it as such.
For example: The member determined that you had the onus of proof for a particular issue, and found against you because you didn't tender sufficient evidence to do so. The evidence itself amounts to a question of fact. The finding that you had the onus is a question of law - which you could phrase as, "That the member erred in finding the respondent had the burden of proof in establishing [situation] under [legal provision]."