I've recently purchased Plisterine and quite like it!
Would be nice to have an update sometime down the road, though.
As a minimum I would love for you to add support for macOS Mojave dark mode (inheriting system settings) and update some parameters (globbing is no longer supported on newer macOS releases).
Secondly, it would be really awesome to address a couple of usability issues:
1) First and foremost is ability to disable prompts of load/reload agents after editing or saving plist file. This is really annoying, as it messes up with workflow.
2) Other minor thing is that script editor disappears when loses focus (when you copy text from other application, for example).
I also would like to suggest things for the big update if you wish to make one.
1) Abstract away from .plist files altogether and just present simple interface with all com.plisterine*.plist files in LaunchAgents folder presented as "Jobs" list in the app. User usually don't really care about underlying technology, he simply wants to schedule jobs or scripts. Of course, using launchd as a base is an awesome bonus, but user don't really need to know about how plist files named, where saved and how they work. This can be explained in a separate section of manual or app itself of course, but it shouldn't be upfront. I propose user add, edit and delete "Jobs" without ever referring to the actual .plist files. I think this can be done even with sandbox limitations in mind, after user grants access to the LaunchAgents folder.
This is actually can be really beneficial for the popularity of the Plisterine since there are a couple full-fledged free launchd plist editors, but they all don't try to solve "I want to launch something on schedule" rather being just GUI for launchctl. I see Plisterine is trying to differentiate itself from them and try to solve "I want to launch something on schedule" problem as a primary goal, but it's not quite there as of now.
2) There is obvious issues of inability to load/unload agents automatically with sandbox limitations in mind. But you can get around it, by simply adding Helper Tool to the website as a separate download. I've seen plenty of devs do just that, and works perfectly. You just tell user, that in order to auto reload he needs to download additional tool.
Would love to hear from you and plans about future of Plisterine.
Sorry for misspelling, I cannot edit original message :(