Sanderd17 : agreed with your suggestion, but the main purpose was to get custom layers for those who prefer staying is JOSM. I would definitely love to see someone using them for browser site.
@Stereo not sure if we can use color styles without downloading the data in JOSM. The idea behind using these layers was to visualize features as a semi-transparent layer without downloading the OSM data.
There are a lot of tools that let you overlay your custom dataset over OSM map. They can be helpful to display paths for events effectively without mapping them on OSM.