The Drupal 6 version of Manuscript is only available from drupal.org/node/376072 as a use contributed conversion from the Drupal 5 version. The theme is an orphan. If you want to use this theme, consider maintaining the theme or sponsoring a maintainer.

This theme fail CSS validation with the following errors.
7 body Value Error : font Parse Error [empty string]
10 #manuscript-header h1 Value Error : font Parse Error [empty string]
11 #manuscript-header h3 Value Error : font Parse Error [empty string]
18 #manuscript-main h3 Value Error : font Parse Error [empty string]
52 h1 Value Error : font Parse Error [empty string]

There is just one HTML error blocking a lot of validations. The following code has a block level element, ul, inside a text level element, span. Change the span to a division.
<span class="taxonomy">
    <ul class="links inline">

Cynthia Says the theme is US 508 and WAI compliant as far as a computer can check.

Wave did not detected accessibility errors.