Missing: Spur 29 Pharr (unsigned?), Spur 69 Austin (unsigned), Spur 97 DFW (unsigned), Spur 200 Roma (unsigned?), Spur 259 Laredo (unsigned?)
Spur 97, despite being unsigned, is already included in USANSF. I'm inclined to walk away whistling casually.

For the rest, I found no signage in GMSV, so they're left out.
Spur 348 Dallas, Spur 408 Dallas
These are already included in the USANSF system, and will be moved over to USATXS when it's activated.
Spur 548 Houston (unsigned)
Unsigned.
Spur 1966 El Paso
This has been on my radar; was waiting for free maps & imagery to improve enough to be able to accurately map it. That, and I hadn't read it was open yet.
Looks like the touchdown point on US85 is just about exactly where the YanDr point is now, so I can just leave it in place and rename it.
Added to my personal branch of the HighwayData repository.
Spur 53 was deleted in 2014: http://ftp.dot.state.tx.us/pub/txdot/commission/2014/1218/15b2.pdf (p. 41)
Spur 66 was deleted in 2014: http://ftp.dot.state.tx.us/pub/txdot/commission/2014/1218/15b2.pdf (p. 46)
Spur 537 was deleted in 2014: http://ftp.dot.state.tx.us/pub/txdot/commission/2014/1218/15b2.pdf (p. 51)
Removed in my repo.
TX16: TXSpr66 -> LoneStarPass
US281: TXSpr537 +-> SanPedAve
Spur 303 west segment east end is at 14th Street, not Belt Line Road.
Hm. Looks like I was going by what's on the Statewide Planning Map. There's no signage for it at, or heading west from, 14th. However, signage at Belt Line (FM1382) unambiguously shows it extending east. Rereading the designation file, I'd say it agrees with your description. Tossing one more source of info into the mix, the
grid map has it ending at FM1382.
Discuss.Spur 471 was created in 2014 from part of FM 471: http://ftp.dot.state.tx.us/pub/txdot/commission/2014/1218/15b2.pdf (p. 2)
Added in my repo.
TX16: FM471 -> TXSpr471
Spur 544's west end is at SH 358. The road west of SH 358 is still signed as SH 44 Bus. (no letter).
TXSpr544 truncated.
New TX44BusCor added, with the existing TX44BusCor renamed to TX44BusWCo.
TX44 point labels changed accordingly.
I'll submit a pull request to make the changes noted above shortly.