Thanks for the report, Richard! I am also able to replicate what you are describing. It’s all “by design” as of today, except for the 5,0 resulting in 0 in firefox which is a bug. That’s a weird one.
Looks like we do need to take another pass through this, to at least update what the admin sees so it is accurate and does not include the separators. Currently you have to refresh your web browser after saving changes to see it.
But I think we can also do more here to help the admin avoid making these mistakes and avoid being confused by them. It feels wrong to me that you can put in “364.5 days” for suggested topics max days old and have that turn into 3645 days. Maybe we just don’t allow non-numbers to be entered in these types of fields.