Text in equation editor always bold

Because the blahtex converter sitting behind that equation editor window can use other text formatting commands:

The \text operator is equivalent to \textbf which uses a bold font. The isolated 123 will be rendered in the default font, and then the following \text resumes the bold font treatment.

Peter,

The equation editor's principal purpose is to allow one to input limited TEX, or MathML equation syntax, and produce inline, translated, equation objects in the Pages document. It is unsuited for passages of text. These document objects, once selected, respond to Pages font attribute changes.

The example that I provided in my previous reply uses the \texttt operator to produce regular, not bold text, and the link in that reply will discuss supported features, with access to the underlying blahtex translator's PDF manual.