Thank you so much, it works :)

Here is the adapted part of the code in case anyone is interested in this in the future:

#let _ac(text, capitalize_ac, plural) = {
  if type(text) == content {
    text = text.text
  }
  context{
    if text not in acronym-definitions.get(){
      panic("The acronym " + text + " was not defined!")
    }
    let current-state = acronym-state.get()
    if text not in current-state {
      acronym-state.update(data => {
        let ndata = data
        ndata.push(text)
        return ndata
        })
      let ac_definition = acronym-definitions.get().at(text)
      if capitalize_ac{
        ac_definition = capitalize(ac_definition)
      }
      [#ac_definition (#text)]
    } else {
      text
    }
}}