Thanks @Bad_Lieutenant for the translation.
I wonder what the negative condition has to do with grain removal. It's easier to remove damage if it's first filtered?
Camera Obscura was going to release one of their Blu's with the grain filtered away and then with added fake grain. Negative was in very bad condition (I think there was even mold on it). But in the end they did this:
"We've talked a lot with our two labs in the last few days and ultimately
decided to abandon all reason and sanity and start the SHORT NIGHT OF
GLASS DOLLS transfer from scratch. This means a new scan with optical
scratch removal tools to reduce defects, scanning the entire content of
the 2P-frame, new filtering of the remaining defects without de- and
regraining. In the end, this means a bitter loss of a couple thousand
euros, 3.5 weeks of lifetime for the manual restoration that was done on
the old master (plus the time for the manual restoration of the new
one), but in exchange, being able to release the discs in all
conscience. And our reputation is always more important to us than
profit. There will definitely be more small remaing defects than in the
first transfer, but therefore the film's naturalness is retained -- the
way we and most of you like it."
EDIT: I also don't understand why Colosseo would have to get the negative to another lab? I don't think any of the scanners have filters in them that cannot be removed. So just scan it again. But I would even think it wasn't filtered during scanning but after and non-filtered files would have at least existed at some point. But who knows.