Create ReportWeek as a calculated table and keep it disconnected from WeeklyQueues.
Create the remaining definitions as separate measures. Import the CSV as WeeklyQueues.

ReportWeek =
DISTINCT ( WeeklyQueues[week_start] )

Selected Reporting Week =
SELECTEDVALUE ( ReportWeek[week_start] )

Ending Backlog =
VAR ReportingWeek = [Selected Reporting Week]
RETURN
    IF (
        ISBLANK ( ReportingWeek ),
        BLANK(),
        CALCULATE (
            SUM ( WeeklyQueues[ending_backlog] ),
            REMOVEFILTERS ( WeeklyQueues[week_start] ),
            WeeklyQueues[week_start] = ReportingWeek
        )
    )

Previous Backlog =
VAR ReportingWeek = [Selected Reporting Week]
VAR CurrentTeams =
    CALCULATETABLE (
        VALUES ( WeeklyQueues[team] ),
        REMOVEFILTERS ( WeeklyQueues[week_start] ),
        WeeklyQueues[week_start] = ReportingWeek
    )
VAR PreviousTeams =
    CALCULATETABLE (
        VALUES ( WeeklyQueues[team] ),
        REMOVEFILTERS ( WeeklyQueues[week_start] ),
        WeeklyQueues[week_start] = ReportingWeek - 7
    )
RETURN
    IF (
        ISBLANK ( ReportingWeek )
            || ISEMPTY ( CurrentTeams )
            || COUNTROWS ( EXCEPT ( CurrentTeams, PreviousTeams ) ) > 0,
        BLANK(),
        CALCULATE (
            SUM ( WeeklyQueues[ending_backlog] ),
            REMOVEFILTERS ( WeeklyQueues[week_start] ),
            WeeklyQueues[week_start] = ReportingWeek - 7,
            KEEPFILTERS ( CurrentTeams )
        )
    )

Backlog Change =
VAR CurrentBacklog = [Ending Backlog]
VAR PriorBacklog = [Previous Backlog]
RETURN
    IF (
        ISBLANK ( CurrentBacklog ) || ISBLANK ( PriorBacklog ),
        BLANK(),
        CurrentBacklog - PriorBacklog
    )

Oldest Open Days =
VAR ReportingWeek = [Selected Reporting Week]
RETURN
    IF (
        ISBLANK ( ReportingWeek ),
        BLANK(),
        CALCULATE (
            MAX ( WeeklyQueues[oldest_open_days] ),
            REMOVEFILTERS ( WeeklyQueues[week_start] ),
            WeeklyQueues[week_start] = ReportingWeek
        )
    )

Opened Tickets =
VAR ReportingWeek = [Selected Reporting Week]
RETURN
    IF (
        ISBLANK ( ReportingWeek ), BLANK(),
        CALCULATE (
            SUM ( WeeklyQueues[opened] ),
            REMOVEFILTERS ( WeeklyQueues[week_start] ),
            WeeklyQueues[week_start] = ReportingWeek
        )
    )

Closed Tickets =
VAR ReportingWeek = [Selected Reporting Week]
RETURN
    IF (
        ISBLANK ( ReportingWeek ), BLANK(),
        CALCULATE (
            SUM ( WeeklyQueues[closed] ),
            REMOVEFILTERS ( WeeklyQueues[week_start] ),
            WeeklyQueues[week_start] = ReportingWeek
        )
    )

Backlog Trend =
VAR ReportingWeek = [Selected Reporting Week]
VAR AxisWeek = SELECTEDVALUE ( WeeklyQueues[week_start] )
RETURN
    IF (
        NOT ISBLANK ( ReportingWeek )
            && NOT ISBLANK ( AxisWeek )
            && AxisWeek <= ReportingWeek
            && AxisWeek >= ReportingWeek - 14,
        SUM ( WeeklyQueues[ending_backlog] ),
        BLANK()
    )

Review Status =
VAR Backlog = [Ending Backlog]
VAR TicketAge = [Oldest Open Days]
RETURN
    SWITCH (
        TRUE(),
        ISBLANK ( Backlog ), "Unavailable",
        Backlog = 0, "No open tickets",
        ISBLANK ( TicketAge ), "Unavailable",
        TicketAge > 10, "Review",
        "Within threshold"
    )