I use KeepassXC, which uses the column names:
"Group","Title","Username","Password","URL","Notes"
Username, Password and URL are the obvious one, which should be added to the FIELD_TO_CSV_COLUMNS.
While trying to look for documentation I came across a page for the old Keepass software, which apparently uses
"Account","Login Name","Password","Web Site","Comments"

Great work implementing this feature.

For reference, KeepassX is a cross-platform port of KeePass (which is written in .NET). KeepassXC is a fork of KeepassX. AIUI, both have a goal of remaining database-compatible with Keepass, so can be treated as roughly equivalent for the purposes of this bug, though a spot-check might be useful to confirm the column headers are the same and import is successful using exports from each KeePass*.

Feel free to submit a patch. It'd be great to include this in Fx80.

Changing to case-insensitive matching would probably address the current format.

I have verified this on Nightly 85.0a1 (Build ID: 20201211213049) and on the latest Nightly 86.0a1 (Build ID 20201215092954) on Windows 10 x64, macOS 10.15.6 and Linux Mint 20.

In order to verify this I have sued the following scenarios:

• I have installed KeepassXC and I have created multiple passwords (with username, without a username, accounts on the same websites).
• I have exported the logins into a CSV file.
• In the latest Nightly 86.0a1 build I have imported the CSV file.
• After following these steps I have verified that the logins are successfully imported.

Considering this I will mark this bug as Verified - Fixed. Please let me know if there are any scenarios that we should verify.