This neighbour who had these improvements approved at the AGM via ordinary motion (??), it should have been a Special Resoloution and SBL registered to confirm that the owner would be reasponsible for the ongoing repair and maintenance of these items. Check the bylaws you recieved when you purchased the property and see if their are any SBL listed.
You say most screen doors are of differing designs implying they were installed individually by the owners rather than the OC (their should be SBL for these as well).
Even if you paid for an EGM what is too say enough will turn up for a quorum or vote to approve your motions (some SM charge $1000 for this service) which would require 75% in favour if the change is to common property (screen on front door)
Find out who is on the EC (listed in the AGM minutes) and try and get 50% to sign a request for an EC meeting to vote your items. I know the EC cannot authorize changes to the common property only the OC can with a 75% vote but I doubt this OC know that (especially if no SBL are registered).
Failing to get a reasonable response from the OC, EC or SM advise them that unless you get a timeline for action within 7 days you will be going ahead with the improvements without approval due to it being a safety issue (burgulary risk).
You cannot go to CTTT to argue your case because you don’t have a motion that has been voted down otherwise I would recommend this route.
I don’t belive they can discriminate against you if others have been allowed free reign and if they took action against you at CTTT you would have plenty of evidence of your reasonableness and OC unreasonableness, as well as evidence of others having done what you are requesting.