The Toei Company has Kamen Rider in knaji for the most part in promotional stuff, the show, movies, toys and manga. But sometimes they romanize it in English as 'Masked Rider.' This was done before Saban's Masked Rider and continued to be after the series. I believe Toei owns the copyright to the words Kamen Rider and Masked Rider. Most of the logos in the Heisei Era has the words in English letters 'Masked Rider' under the Kanji of Kamen Rider.
But when Kamen Rider Ryuki was going to be adapted by Adness Entertainment, Toei wanted to separate the name 'Masked Rider' from the adaption from Saban's Masked Rider and romanized the Kanji to 'Kamen Rider.' Some fans were upset CW4Kids chose to say 'a uncommon hero' to go along with the pronunciation of 'Kamen' as Common. Above is a picture where you can clearly see English letters 'Kamen Rider' in official merch.