The way the search results functionality works is that it totals both "Full Baths" and "Half Baths". So if the field "Full Baths - 11" Half Baths - 1" it will count as "12 Total Baths".
It is possible to do 11 full and 1 half bath as 11.5 for example. However, if there were 2 Half Baths and the system counts them as 0.5 + 0.5, it would equal 1 bathroom which would not be accurate.
Thankfully your property detail page clarifies the bathroom breakdown.
Please contact firstname.lastname@example.org if you would like to discuss changing how this looks on your site.