Hi,
That page looks to me like you have developed a custom feature without following recommended guidelines. I don't think those character problems are related to the charset or language declared in the page. I would review how that data is generated, ie if it is stored in an ascii file or in a database table that doesn't support utf or uses varchar instead of nvarchar. Included features in mojoPortal don't exhibit problems with non ascii characters so it is something about your implementation.
But aside from that I do not recommend implementing features in such a way that you pass extra parameters to a CMS page, none of the included features do that. You should use a supporting page instead just like all features that we ship in mojoPortal such as the blog, forums, webstore that need extra params we do not use the CMS page for that, we link to detail pages. The CMS page is just the entry point to the feature it contains the module control which is the entry point of the feature and does not expect additional parameters. The module control should link to the supporting page and pass any needed extra params in addition to pageid and module id (mid). Note that the CMS page has a cannonical url that does not include the extras paramter you are passing which means search indexes will not see the different content from different params. You can get away with developing like that if SEO is not a concern for your feature but it is not the way I recommend doing things.
Hope that helps,
Joe