No, 'Open Roosendaal Castle' does not exist, therefore it cannot be wheelchair accessible.
Accessibility features, including wheelchair ramps, elevators, and accessible restrooms, are attributes of physical locations and structures. Since 'Open Roosendaal Castle' is a fictional entity, it possesses no physical form and consequently no accessibility features for wheelchairs or any other mobility aid. For real destinations, accessibility is a crucial factor for many visitors, but in this case, the question cannot be answered affirmatively due to the non-existence of the subject.