At the moment, what can be done instead is a simple plugin to expand ALL records:

class AutoExpandFilterLayer:
	doc.Layer,
	log.FoldingFilter {

	ui.BoolProperty* m_expandProp;

	construct(doc.PluginHost* pluginHost) {
		basetype.construct(pluginHost);
		m_expandProp = pluginHost.m_propertyGrid.createBoolProperty("Expand all records");
		pluginHost.m_log.addFoldingFilter(this);
	}

	override void restoreDefaultProperties() {
		m_expandProp.m_value = true;
	}

	override uint8_t filter(
		uint64_t timestamp,
		uint64_t recordCode,
		void const* p,
		size_t size
	) {
		return m_expandProp.m_value ? log.FoldFlags.ExpandAll : 0;
	}
}

Here's an archive with the full plugin:

AutoExpand.7z

After attaching it, all the new foldable records will be expanded by default. You can check/uncheck the "Expand all" property and rebuild the log to expand or collapse all foldable records.

Hope this helps!