Got the listing through an edit page and modifying guid parameter :) Yes it is a legitimate former school WM listing, although the english text looks like a product of Google translate.
The building no. 135/I is first mentioned in 1570 as an Utraquist (see
http://en.wikipedia.org/wiki/Utraquism ) school and several important renaissance personages were teaching there. Later in 1622-1784 it was used as Catholic Trivial School. In 1784 the house was damaged by a large fire in Rokycany town and "Dumetovsky dum" house nearby, which survived the fire, was used as as a school in 1784-1787. In 1788, a new school was built (currently used as a museum). However, this old school was still in use until 19th century. In 1820s the schoolhouse was rebuilt in Classicism style and later it was used as a church archive, an arts and music classes school, and currently a museum archive is located there.
The mentioned source website rokycanyhomepage.ic.cz doesn't exist but the same information is at
http://www.hrady.cz/?OID=10586.