I don't think this belongs in after-1900. Alternate alphabets, rather than recent spelling reforms, would go in before-1900.
By the way, Old English got very, very little vocabulary or grammar from Celtic languages. There's not much evidence of a Celtic substrate - just a handful of borrowings, plus some place names. Old English already had more Latin-dervied vocabulary, usually for religious purposes ("psalm"), than Celtic vocabulary. I also dislike the reference to German as an influence: English and German both descend from a common ancestor, but did not influence each other much until the modern era, and then the influence has been more English on German than the reverse. It's nothing like the situation with French, or for that matter Old Norse, which contributed vocabulary to English well after they'd diverged (millennia in the case of French).