Generally I would expect a FHIR Questionnaire's questions' text to be static (i.e. a PHQ-9 Questionnaire). However for non-standardized forms, such as an intake specific to one clinic, there could be questions where the text should be personalized for user experience.
A scenario would be a parent / guardian filling out an intake for their pediatric dependent. For a more personal touch, the question text could be something like "Please tell us John's height".
There's two approaches I can think of to make this work with FHIR Questionnaires:
Create pseudo-templating business logic within a Questionnaire. This would require any consumer of this resource though to understand the templating. For example:
Generate personalized FHIR Questionnaires off of a reference / static Questionnaire. This Questionnaire would still include something in the text indicating it needs to be replaced, but each intake would generate a copy of that reference Questionnaire, populating the text as needed, and serving this personalized copy to the patient.
Are there any other options for these types of scenarios?
There's a standard extension for doing what you want to do. If you look at the SDC Advanced Rendering profile, you'll see there's a cqf-expression extension on the item.text element. That allows you to specify a FHIRPath or CQL expression that determines what the rendered text ought to be. (You can do the same thing for a bunch of other element on the Advanced Behavior profile.)
Also take a look at the SDC section on expressions which will give guidance on how to set some of those variables using things like the launch-context extension.