Screen readers use HTML Section Heading elements (e.g. h1, h3, etc.) to specifically announce content as headings. PX is using div elements (e.g. .px-tooltip-title-wrapper) as containers for titles, so the screen reader does not read them as headings. This reduces accessibility. Consider the Guide tool tip, for example. The distinction between the title and the body text is pretty critical.
The workaround is to disable the title and manually code a heading element into the body of the engagement. This works in theory, but in practice this would need to be done for every localization version of every engagement, making it relatively impractical.