I know this would be difficult to implement, but you should consider implementing various other coin types, as well as potentially a mechanical coin press that could maybe give coins a metadata id to prevent counterfeiting on servers where it's illegal?
This mod for terra firma craft has a coin press that's a great representation of kinda what im talking about, with specific coin molds that can be duplicated but not recreated from scratch
https://terrafirmacraft.com/f/topic/7563-tfc-07923-merchants-addon-for-tfc/?__cf_chl_managed_tk__=pmd_3v68Rb_htLHAtyz1qf7Jqia0u4SLDlru.2sIFvdeofs-1631579576-0-gqNtZGzNAuWjcnBszRSl