maybe i'm wrong but the "mapper" as i understand it, is a ic that controls how rom data is delivered to the nes and depends on the hardware pcb layout on a real cartridge (ie memory requirements and special features). so patching and the like is only needed if the target does not understand how to handle the incoming data. that is why some pc emu cant run some roms correct. once they got "mapper update" the same dumped rom without any patches runs with no problems. for example the pc emu fceux had no support for mapper 31 until v2.2.3. mapper 31 roms did not work correct in prior releases. now they do.
the victor version which also got a us release works (both mapper 4), but the namco jp exclusive version does not work (mapper 19). i dont know about "everyone" but i prefer the english patched namco version