1. `copy_cache` in `models.py` recursively copies the caches to environment, 
2. which in
```python
def _compute_related(self, records):
        """ Compute the related field ``self`` on ``records``. """
        others = records.sudo() if self.related_sudo else records
        if records.env != others.env:
            copy_cache(records - records.filtered('id'), others.env)
        values = list(others)
        for name in self.related[:-1]:
            values = [first(value[name]) for value in values]
        for record, value in zip(records, values):
            record[self.name] = value[self.related_field.name]
```
3. copies failing cache values that have been produce previously by this line:

`models.py : def _prefetch_field()`
```python

        try:
            # THIS ONE
            result = records.read([f.name for f in fs], load='_classic_write')
        except AccessError:
            # not all records may be accessible, try with only current record
            result = self.read([f.name for f in fs], load='_classic_write')
```
I checked it's exactly the same `FailedValue` object, which is later accessed without intent (not refreshed) by the fact that the buggy environment is copied to sudo (and not refreshed).


if 'translate' in kwargs and not callable(kwargs['translate']):
            kwargs['translate'] = bool(kwargs['translate'])
        super(_String, self).__init__(string=string, **kwargs)
    _related_translate = property(attrgetter('translate'))
    def _description_translate(self, env):
        return bool(self.translate)
    def get_trans_terms(self, value):
        """ Return the sequence of terms to translate found in `value`. """
        if not callable(self.translate):
            return [value] if value else []
        terms = []
        self.translate(terms.append, value)
        return terms
    def get_trans_func(self, records):
        """ Return a translation function `translate` for `self` on the given
        records; the function call `translate(record_id, value)` translates the
        field value to the language given by the environment of `records`.
        """
        if callable(self.translate):
            rec_src_trans = records.env['ir.translation']._get_terms_translations(self, records)
            def translate(record_id, value):
                src_trans = rec_src_trans[record_id]
                return self.translate(src_trans.get, value)
        else:
            rec_trans = records.env['ir.translation']._get_ids(
                '%s,%s' % (self.model_name, self.name), 'model', records.env.lang, records.ids)
            def translate(record_id, value):