oTree: USE_POINTS=True in one app and False in another?

Question

I'm designing an experiment in oTree which uses points during the main part but in the questionnaires, I'd like it to use currency instead.

The last thing I tried was this, in settings.py:

for app in SESSION_CONFIGS[0]["app_sequence"]:
    if app == "A05_Questionnaires":
        USE_POINTS = False
    else:
        USE_POINTS = True

and then

altruism1 = models.CurrencyField(max=100, label="blabla", blank=True)

Interestingly, this did not lead to any error messages but oTree seemed to choose randomly whether to use currency or points this time.

I also tried using a FloatField for altruism1 instead and restricting it to two decimal places:

altruism1 = models.FloatField(max=100, label="blabla", blank=True)

and then in the Page class

@staticmethod
def error_message(player, values):
  if round(values["altruism1"], 2) % 0.01 != 0:
    return("error message")

but this produces a floating-point error I guess - there's always some deviation from 0.

[EDIT] I also tried some JavaScript in my template, adding an extra confirmation button before submitting the form in order to check the input, but I quickly gave up because a) pressing Enter still evoked the same error messages as before, ignoring my button completely and b) the button did nothing yet:

{{ block title }}
    Page title
{{ endblock }}


{{ block content }}
<p>
    {{ formfield "altruism1" }}
    {{formfield "altruism1_noanswer" }}
{#    <div id="donation-button" style="visibility: hidden;"> <input type="button" value="confirm" onclick="onClickCheck()" onkeypress="onClickCheck()"> </div>
#}
</p>

<div id="next-button" style="visibility: hidden;">  {{ next_button }} </div>

{{ endblock }}

{{ block scripts }}

<script>

let altruism1Select = document.getElementById("id_altruism1")
let altruism1NoanswerSelect = document.getElementById("id_altruism1_noanswer")

altruism1Select.addEventListener("click", function() {
    forminputs.altruism1_noanswer.checked = false;
    document.getElementById("next-button").style.visibility = "visible";

    forminputs.altruism1_noanswer.required = false;
    forminputs.altruism1.required = true;
});

altruism1NoanswerSelect.addEventListener("click", function() {
    altruism1Select.value = "";
    document.getElementById("next-button").style.visibility = "visible";
    document.getElementById("donation-button").style.visibility = "hidden";

    forminputs.altruism1_noanswer.required = true;
    forminputs.altruism1.required = false;
})


function onClickCheck() {
    if(forminputs.altruism1.value.isNaN() = false){
        if(forminputs.altruism1.value % 0.01 != 0) {
            alert("Please enter a number with two decimal places or less.");
        } else {
            document.getElementById("donation-button").style.visibility = "hidden";
            document.getElementById("next-button").style.visibility = "visible";
        }
    } else {
        alert("Please enter a number with two decimal places or less.");
    }
}



</script>

{{ endblock }}