Taxonomy Filter term/147,122 VS term/147+122

As far as I can see it is nothing to do with taxonomy_filter.

If your /taxonomy/term/x,y url is actually giving you /taxonomy/term/x+y, then it is either a bug in the core taxonomy module (unlikely) or some other module you've installed is affecting the listing.

What result does that url give you when taxonomy_filter is turned off?

taxonomy_filter just gives you the url to click on - it doesn't actually serve that url or do anything to define the listing at that url (that is normally handled by the core taxonomy module). So if the url is 'right' but the listing is 'wrong', then the problem is elsewhere.

The only thing taxonomy_filter does is produce the block full of links.

Also: I notice you are using tf_multi and tf_count together - you'll notice those two don't work properly together (see the README.txt) the result numbers are wrong/undefined/ambiguous. The only real solution is to change the way tf_multi works - eg ditch the +/- links and use the term name to do the add/subtract bit.

Download tonight's dev release (see #447896: Change base menu template to display a refine search block and show the current search criteria) and post back whether this works as you expect. Use the base menu template, enable the tf_multi module, and also enable the tf_count module to display the counts. You will get a new display at the top of the page that shows the current search criteria. Let me know if this is useful for you or if it you would prefer it be optional.

Also, the '+' link and the criteria name link now do the same thing (I intend to make this into one link with the '+' sign text set in the admin settings page.)

Let me know if this change works for you or how we need to modify it.

Could be a view handling taxonomy.
The default system view for taxonomy does this.
You must replace the taxonomy field with depth to one without depth.

The display should be optional in tonight's dev release. Several new configuration settings too. You will need to run update.php.

Let me know.