The type there does not mean participant user. You can get the license type information from the user_licenses table, though it's in the form of GUIDs.

If the Forms Participant license is assigned in LFDS, and the users are signing in to Forms using Single-Sign On, then you could try the following query:

select a.sid, a.name, l.type, u.last_login

from dbo.account_cache a
inner join dbo.user_licenses l on a.sid = l.sid
inner join dbo.user_logins u on a.sid = u.sid

where l.type = 'dde75261-70e3-49f5-84bc-d8ef36f1aa56'

Note that if you have subscription Participant users, this is not the right GUID. It is unique per master license.

You can find the right license type ID for your system by querying for a specific user that you know has this type of license:

select a.sid, a.name, l.type

from dbo.account_cache a
inner join dbo.user_licenses l on a.sid = l.sid

where a.name = 'ReplaceWithUsername'