You can use per_empl_configurations table to verify the versions of Seniority dates/ Termination dates.
Below is an example to check the version for Termination dates:
select version_code
from fusion.per_empl_configurations
where configuration_type = 'ORA_TERMINATION'
If the version code value is NULL that means you are still on version V2.
Same table can be used to query Seniority Dates version.
select hr_general.decode_lookup('ORA_PER_SENIORITY_ITEMS',psds.seniority_date_code) seniority_date_code_meaning
,hr_general.decode_lookup('ORA_PER_SENIORITY_LEVELS',psds.level_code) level_code_meaning
,hr_general.decode_lookup('ORA_PER_TRIG_FIELDS',psds.triggering_field) triggering_field_meaning
,psds.active_flag
,psds.allow_edit_flag
,psds.display_in_ui
,psds.cumulative_flag
,psds.hours_in_year
,psds.hours_in_month
,psds.hours_in_day
,psds.object
,psds.source_field
,psds.seniority_version
,psds.record_creator
,psds.setup_seniority_basis
from per_seniority_dates_setup psds