@Casmat nice. if you want you can post the hallucination bugs and I'll add them to the MCP servers in the DONT section - that's an iterative process but since I'm working mainly with the Claude models it might be overfitting to their behaviour.
I'm also inclined to change the scripting language to support more "JS-type" constructs granted that it doesn't affect backwards compatibility and is within the scope of HiseScript - that's the gold standard of removing friction points, a DONT section in the unified style guide is a band-aid.
But the first line of defense against hallucinations should be the LSP server - this is another binary that is integrated with your coding agent and is executed after every file edit. This doesn't recompile HISE (and you have to disable the "recompile on file load" function in HISE for this to work), but it "shadow parses" the edited file and returns a multi-error diagnostic log with all syntax errors or hallucinated methods. It doesn't do real runtime inspection, but it catches missing API methods as well as a few custom diagnostics.
RE: your initial feature request. Have you checked using the Viewport's multicolumn mode for preset browsers? this should be vastly more efficient and is suitable for displaying hundreds of preset items without performance issues. ScriptPanels are too heavyweight to be used for a single row in high numbers.