This data explorer query will go a long way towards giving you what you need:
-- [params]
-- int :topic_id
WITH user_emails AS (
SELECT
ue.user_id,
ue.email
FROM
user_emails ue
WHERE
ue.primary = true
),
forum_timezone AS (
SELECT
value AS timezone
FROM
site_settings
WHERE
name = 'discourse_local_dates_email_timezone'
)
SELECT
u.name AS display_name,
u.username,
ue.email,
CASE dpei.status
WHEN 0 THEN 'Going'
WHEN 1 THEN 'Interested'
WHEN 2 THEN 'Not Going'
END AS status,
to_char(dpei.created_at AT TIME ZONE 'UTC' AT TIME ZONE ft.timezone, 'YYYY-MM-DD HH24:MI:SS') AS rsvp_timestamp
FROM
discourse_post_event_invitees dpei
JOIN
posts p ON p.id = dpei.post_id
JOIN
users u ON u.id = dpei.user_id
JOIN
user_emails ue ON ue.user_id = dpei.user_id
JOIN
forum_timezone ft ON true
WHERE
p.topic_id = :topic_id
ORDER BY
dpei.status, ue.email
If you make a group for your admins staff, and make this query accessible to them it will likely do the job nicely. You’ll probably want to set the Discourse Local Dates Email Timezone setting (or hack the query to ignore it).
You’ll need to teach them to use the Topic ID, and what that means in terms of URL. But that is probably doable.