The full version of Spine (both ESS and PRO) allows you to run any older version, so you could run 3.8, import the 3.8 data, save a project file, and open that with the latest 4.1.
The trial is always the latest version, sorry. If you purchase Spine, you have 30 days to request a refund. Otherwise you could try loading the data using the 3.8 runtime, so you can see what your spriter2spine script has done to your animations.