How to save multiple values when pressing the submit button?

Yes, you can perform multiple saves on any component that has a saveInto parameter.  

Using your button as an example:

primaryButtons: {
  a!buttonWidget(
    label: "Submit",
    submit: true,
    style: "PRIMARY",
    value: loggedInUser(),
    saveInto: {
      ri!cdt.typetext,
      local!user,
      a!save(
        target: ri!cdt.typeinteger,
        value: 123
      ),
      a!save(
        target: ri!cdt.typeboolean,
        value: true
      ),
      etc...
    }
  )
}

In this example, loggedinuser() would save to both ri!cdt.typetext and local!user because it will reference your 'value' parameter when you do not use an a!save() function.  The a!save() functions then allow you to save data to any values to any available variables.

See this documentation as well: docs.appian.com/.../enabling_user_interaction.html

Thank you!

On the saveInto field of your primary button, make your save statements like this:

a!buttonWidget(
label: "Submit",
submit: true,
style: "PRIMARY",
value: loggedInUser(),
saveInto: {
a!save(ri!value1, "value1"),
a!save(ri!value2, "value2"),

a!save(ri!value3, "value3"),

a!save(ri!value4, "value4")
}
)