That Knowledgebase article is dealing with voiding credit memos or debit memos.   You cannot void a credit memo but you can reverse it by doing an opposite transaction (debit memo)  to the the open credit or invoice and distribute it to the same posting accounts as the original credit memo.

Does this Solution apply to Sage 100 as well? We also have experienced an issue where a credit memo was applied to the incorrect invoice and then posted. We weren't sure if the above would solve the issue.

This would only apply to Sage BusinessWorks.  You may want to post your question on the Sage 100 community.