This is an awesome post.
To answer your final question, I'd speculate that your answer is "yes".
That said, I probably would have pursued soft numa before resorting to the trace flags. I think you are right about the numa node allocation and that's could be at the root of your problem. Via soft numa, you could scale out the requests, depending on your count of numa nodes (4?) - to 4, if that's the correct number, and then assign, via ip address, each host to a specific numa node, in addition to that, I'd disable hyper threading. Combined, the issue would likely decrease, however, it would do so at the cost of fewer schedulers.
On a seperate thought, I'd look at forced parameterization - the fact that your load is driving your CPU so high is very interesting and it may be worth looking into that.
Lastly, on multi-numa node systems, I typically have the output of the following queries dumping to a table every N seconds. Makes for some interesting analysis when workload changes or trace flags are implemented:
SELECT getdate() as poll_time, node_id, node_state_desc, memory_node_id, online_scheduler_count, active_worker_count, avg_load_balance, idle_scheduler_count
FROM sys.dm_os_nodes WITH (NOLOCK)
WHERE node_state_desc <> N'ONLINE DAC'
and
SELECT top 10 getdate() as sample_poll, wait_type, count (*)
FROM sys.dm_os_waiting_tasks
WHERE [wait_type] NOT IN
('CLR_SEMAPHORE','LAZYWRITER_SLEEP','RESOURCE_QUEUE','SLEEP_TASK','SLEEP_SYSTEMTASK',
'SQLTRACE_BUFFER_FLUSH','WAITFOR', 'BROKER_TASK_STOP',
'BROKER_RECEIVE_WAITFOR', 'OLEDB','CLR_MANUAL_EVENT', 'CLR_AUTO_EVENT' )
GROUP BY wait_type
ORDER BY COUNT (*) DESC
As far as I know, trace flags 8722, 8755, and 8602 were never officially documented. The last time I remember 8722 and 8755 being effective was in SQL Server 2000, so it is not surprising you find they are ignored in SQL Server 2012. Trace flag 8602 is still functional in SQL Server 2019 as a global or start-up flag to ignore index hints specifically.
For specific query patterns, it is often possible to remove the FAST n hint using plan guides. Even so, the best fix is to get the AX developers to fix it on the application side of things.
Best Answer
All should be turned off until you know why they should be implemented. Now if you inherit a server with a couple of trace flags on, do not just turn them off if you do not why they are there.
On a new server, knowledge first, then trace flag on. On a old server, leave as is, knowledge, make decision.