I think what @RGJ is suggesting is to invest in updating your CMS integration to be compatible with the latest Discourse, as most developers try to develop for the latest tests-passed or stable releases of Discourse.
We’re currently updating and deprecating various developer APIs and tooling, so developing a new theme for a site that’s four major versions behind (v2.8 is out next week) is going to be expensive for both you and the developer in terms of time and money, as well as most likely being unsupportable going forward.
While sticking on an older version is nice for compatibility, we’d definitely recommend fixing the integration that has stuck you to an old version so you can continue getting support from our awesome developer community going forward. Not to mention to make sure your site gets the latest features and security patches!