Couple of things. The stirling grand template is not identified to be compatible with ZC 1.5.4, but that doesn't mean it can't work, just that perhaps there might be some issues.
At least one issue with "images" was recently found in the related template thread:
https://www.zen-cart.com/showthread....31#post1278531 that post contains links to two separate things, but may be related or fix a problem not yet known about. :)
Some tests were requested to to be run related to EP4; however, it doesn't appear that the results were presented. That being: load an image path for a product using EP4, download the result, manually access/save the product, download the result. Compare the two downloaded files. What's the difference? Nothing? Then there probably is something else that the template has/does that needs to be addressed...