There is a reason most in the US are going to using a translation wireless system. Channel one is English, channel eight is Spanish (8-64 channels are available depending on the system you buy). Unlicensed FM transmitters also work well for this. You need to make sure you don't conflict with other nearby users, but that generally is easy (and if there is a possibility you should have an agreement to have your "Christmas pageant" on different days so you can borrow each others receivers for the busy time thus saving both of you money).

Auracast looks like the future of this, so make sure anything new you get supports that. Those so few systems support it don't expect much of it - you should demand this to ensure the manufactures know there is demand, long term it is better for everyone to use one standard.