kurtseifried

Sitemap to RSS Converter allows you to transform XML sitemaps into RSS feeds using predefined aliases. This is particularly useful for monitoring updates to websites that only provide sitemaps but no RSS feeds.
Features:
<ul>
<li>Create aliases for your sites that have sitemaps but no RSS feed</li>
<li>Simple and clean admin interface</li>
<li>Secure by design – only approved sitemaps can be converted</li>
<li>Easy to use and maintain</li>
</ul>

sitemap2rss

Convert XML sitemaps into RSS feeds using predefined aliases.

kristarella

Copy or convert terms between taxonomies.
Taxonomies include categories, tags and any other custom taxonomies that may be present with your active theme and plugins.
This plugin, based on Categories to Tags Converter, allows you to copy (duplicate) or convert (move) terms from one taxonomy to another or to multiple taxonomies, while maintaining associated posts.

Taxonomy Converter

For starters, the plugin has deprecated code and produces errors on PHP7. Looks like the code hasn't really been touched all that much in many, many years.

The biggest problem is that when the terms are converted, the term descriptions are removed.

Doesn't include term descriptions

Copy or convert terms between taxonomies.

sitemap2rss vs Taxonomy Converter