As an example I've choosed the style Social. We will remove all the customized templates in it.
First we need to import the style and install Template Modification System.
Now go to customized components and see 3 custom templates.
Let's compare them with original using http://diffchecker.com/diff
Take a look at node_category_level_1 and see that category description moved 2 divs down and wrapped into <div class="descriptionContainer">
Now we create template modification doing the same thing. It is convenient to use regular expressions with modifier "s" (enables "single-line mode"). Modification is illustrated in the picture.
Create similar modifications for EXTRA.css and form.css.
At the moment modifications may not be applied since they try to search in custom templates of style Social but they differ default ones. To apply them delete the customized templates from Social.
Now we see all of them work fine. And style looks same. To check it we use "diff" links in the list of modifications. When you export/import the style modifications go with it. From author's permission I attached the EditFree version as demo.