function toLanguage(text) {
    return text.replace(/[^aeiou]/g, function(pattern) { return pattern + "op" })
}

function toEnglish(text) {
    return text.replace(/[^aeiou]op/g, function(pattern) { return pattern[0] })
}

const inLanguage = "dopavopidop"
const inEnglish = "catherine"

console.log(toEnglish(inLanguage)) //david
console.log(toLanguage(inEnglish)) //copatophoperopinope