Vocabulary in The Yellow Wallpaper
Arabesque art and architecture is characterized by the use of floral imagery in elaborate, interlacing patterns. In that sense, the use of the word "florid" here is redundant, but does indicate that the narrator feels disdain towards the pattern and finds it ugly (as indicated when she likens it to fungus).
A state of confusion and psychosis generally brought on by withdrawal from alcohol or narcotics. Using this term in relation to the debased Romanesque art suggests that the wallpaper pattern is particularly chaotic and confused.
Romanesque art flourished from approximately 1000 AD to the middle of the 13th Century, when Gothic art became prominent. Romanesque art is characterized by the use of primary colors, flourishes, natural imagery, and architectural patterns. Since religious and Biblical iconography were common is Romanesque art, the description of a "debased" Romanesque suggests an unholy pattern, something that isn't sanctified or harmonious.
Hysteria was once a very common medical diagnosis ascribed to women who displayed certain unruly habits and behaviors or seemed to be suffering from a nervous condition. Hysteria was thought by the ancient Greeks to be caused by a "wandering womb" and was in the 19th and 20th Centuries treated with "massages," many of which were performed with vibrators.