There query appears to be missing an alias:
SELECT o2a.SOURCE_ID source_id, o2a.VALUE 
FROM CR2Copy..OBJECT_TO_ATTRIBUTE

should be
SELECT o2a.SOURCE_ID source_id, o2a.VALUE 
FROM CR2Copy..OBJECT_TO_ATTRIBUTE AS o2a

How about some data? CREATE TABLE and INSERT scripts?
Why not do the CASE statement in an inner query, and then pivot that result?

DISTINCT is going to be brutal slow.
AND o2a.STATUS_ID = 33000000000001 AND o2a.PROPERTY_ID = 1000000060338
AND o2a.SOURCE_ID
and then are those columns indexed? (maybe included in PK index?)

Wait, if you want a cumulative sum, your formula is wrong. There's no ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW in there... Is there are hierarchy in this? Can you...

Go back and ask said DBA why he wants this. Sounds absurd. The nice thing about stored procedures is that you can assign rights to them. you can't do that...

If you have a Calendar table, this is infinitely easier. You would outer join Calendar to your Trips table and then aggregate on columns in the Calendar table (Year, Month,...

You need to calculate the month from the date. A date is just a number...

SELECT MONTH(start_date), COUNT(*) AS Count
FROM trips
WHERE YEAR(start_date) = 2016
GROUP BY MONTH(start_date);

.What if you automated Excel to write the values somewhere? Assign the values to variables (one for the file name too), and then maybe have a connection to your database...

If you add a Calendar table and put the FM, FY in there as columns, then this is trivial.

Are you just adjusting for a Fiscal Year or similar? You could do that with a Calendar table.

Essentially, you're just checking if the Customer has Instore sales and/or Online sales?
Can't you just do that with IF(COUNTROWS(RELATEDTABLE('Sales'))>1,1,0) and put it in the Customer table?  You might need...

SQL Sat Nashville is tomorrow... if you run fast, you could probably squeeze in a session or two.

Did you run the code to create the function? Sounds like you didn't.