At present both 'figan' and 'fegan' are used as nouns and both 'figanaidd' and 'feganaidd' are used as adjectives.
Over time one spelling will become preferred I imagine. They're both right on this course.
I'm very sorry, I thought I had typed "fegan", but I must have made a spelling mistake.
What I meant was at the moment both 'fegan' and 'figan' are correct. Often when a new word is adopted to the language both a phonetic version is suggested, in this case 'figan' and an adaptation is suggested, in this case 'fegan' since Welsh has no 'v'.
Usually over time one version becomes more popular than the other and becomes the standard.