Actually, nobody even went as far as saying "latinum can't be replicated".
For all we know, it can, just like hundred-dollar bills can be printed.
Latinum is not a currency, it's a rare material, like diamonds.
Diamonds are nothing more than pressurized carbon and are one of the most abundant materials in the universe (which includes our planet Earth).
Also... Humanity has been creating synthetic diamonds since the 1950's for industrial applications - while it wasn't until the early 1990-ies that we gained the viable ability to use them in electronics (and for other purposes) - which due to the monetary system we live in have YET to live up to that use because current industry still isn't done with milking money out of Silicon.
As for latinum being non-replicable... I don't think there was any mention of it being non-replicable.
Ferengi merely use it for currency, and those who want to do business with the Ferengi need to utilize gold-pressed Latinum.
Its possible that the Ferengi have officials who know replicators CAN create gold-pressed latinum, but it would be something kept hidden from their general public.
Also, 'Night of Terrors' essentially confirms that Federation replicators merely need energy (large portions of it) to synthesize matter (because they transform energy into matter as it was repeated several times) and do not require existing portions of matter (organic or otherwise) to create something.
The more complex a material or element is that you try to replicate, it requires that much more power - Enterprise had an issue with its power being depleted on a regular basis and replicators simply didn't have enough of it to synthesize the required elements.