is the t-junk ok?

I guess with t-junk you refer to mesh endpoints landing on a mesh line of another structural part instead of an endpoint of that other structure. While I understand that this is not how mesh networks should be designed since some mesh algorithms can't deal with that situation gracefully. I was not aware that this is a consideration for the LDraw library since I found that all parts using studs, even the most basic ones like 3001.dat, have the studs free standing on a plane surface, effectively having mesh points not even on a line but only on the surface of the other objects, which is an even more critical issue for the algorithms mentioned.

As such my approach as a new parts submitter with a background as a software engineer was to apply minimal changes to the existing part to fix the problem I detected with minimal impact otherwise. If instead, the approach in the LDraw library is to fix all issues a part might have I would appreciate it if you pointed me to a clear criteria list I could consider.

For transparency, this is the history of the changes that I exchanged with Orion by mail since this is an update for an existing part:
step 1: I submitted the part with only the fix applied for the missing bump with the message: "I found that the hinge on parts/4214.dat is missing the bumps it needs to hold its counterpart, like parts/4214.dat. Since the part parts/4315.dat with the same hinge type has those bumps I decided to port that one back to parts/4214.dat."
step 2: Since Orion pointed out that the parts tracker does only accept CCW parts but the original was still CW I inverted the faces and made a second submission with the message: "Thanks for pointing that out. I inverted all faces now and changed from CW to CCW. The resulting file and new patch are attached."

I can do further cleanup steps if desired but before starting to fix something that requires fundamental mesh restructuring like fixing your mentioned t-junctions I would appreciate being pointed to a clear criteria list to avoid an endless frustrating redesign loop.

To be clear: t-junk is neither contrary to the spec nor holdable here on the PT.

While they are discouraged for new parts (and, yes, I realize that there are common exceptions), as this is a part fix, fixing them is not a requirement.

Yes, not holdable, not required to be fixed, but much appreciated if it's fixed.

I see little or no t-junctions that need to be fixed...

It was a general comment, not specific to this part.

where the hinge fingers meet the upper column, does that count?

Imho, no. In this configuration, they will generate no visual problem, and doing so lowers the number of surfaces to render.

So, I have now a modified version available with all t-junctions eliminated. But as Philo correctly points out this increases the number of faces. You make the decision now, whether you want the fixed version with more faces or keep the unfixed one as it is now.

Ok, when trying to upload the updated version I get "4214.dat: Invalid/missing author line". I didn't change the author line with my changes compared to what is here in the parts tracker now. Am I supposed to do so? Should I put my name here? (I didn't want to remove the attribution to the original author.)

Any hint about how to fix this author line issue on my side would be highly appreciated.

* T-junk

* Could use boxes for all:

4 16 2 0 10 2 -4 10 2 -4 2 2 0 2
4 16 -2 0 2 -2 -4 2 -2 -4 10 -2 0 10
4 16 -2 0 10 -2 -4 10 2 -4 10 2 0 10
4 16 -2 -4 2 -2 0 2 2 0 2 2 -4 2

* Should use 2-4chrd for 2-4discs

* All cyli+edge combinations should be substituted by cylo(s).

* The 0 comments for blank lines are no longer required, especially the 0 at the very end.

Looks like there's an issue with the author line generation for legacy users (of which James is one). I'll figure out the problem and push a fix

Author bug fixed.

Surface edge bleeding here:
2 5 36 0 10 36 4 10
2 5 36 0 -4 36 0 2
2 5 -36 0 10 -36 4 10
2 5 -36 0 -4 -36 0 2

These 2 surfaces need to be divided to avoid that bleeding
4 16 36 40 -10 36 0 -10 36 0 10 36 40 10
4 16 -36 40 10 -36 0 10 -36 0 -10 -36 40 -10

does the t-junk at the upper link count? where the hinge fingers meet...

Fixed surface bleeding, used more primitives, removed T-junctions
(Official file fix, Was held more than 3 months after upload issue was fixed)

the inverted cylos have some bleeding to the side quads -> should the quads get cut out from behind the cylo? only one additional triangle per side...

Cutout inverted cylos as suggested