Hi,
The Square plugin is developed by our partner Tsukidev:
www.hikashop.com/marketplace/product/235-square.html
Most of the issues with the plugin that I can find reported on this forum comes from newer versions of Joomla, or server setup (like openssl missing), or PHP or changes with the Square API which the developer had to take into account to update the plugin.
The last one, a month ago was precisely because of the old API of Square being stopped, followed by Tsukidev releasing a new version of the plugin with support for the new API:
www.hikashop.com/forum/payment-methods/9...stopped-working.html
So as far as I can see, the plugin is still maintained and working, and is being used by dozens of merchants.
Note also that we have a 30 days money back policy here:
www.hikashop.com/money-back-policy.html
So you can purchase it, try it, and ask for a refund if it doesn't work out for you.