Here are a few ideas to improve the implementation:
1. In the info box, it shows your income (gross) and your number of shares. Gross income is not useful, that should report your NET income (and in case people are confused, the tooltip could SAY it's "net" (with the stock subtracted off)

2. Auctions in asynch play take forever, and it's lame to log in just to make a bid... No Thanks has a thing where you can kinda put your max bid, and the game will bid for you so you don't have to keep logging in each time. Perhaps that could be done here, toggleable (in case you don't want to do that) - you could enter a max bid and an increment, and when your turn comes around, the game will up your bid by the chosen increment (as long as that's not over your max bid, in which case it just bids your max bid). That would speed up the auction for asynch a lot!

3. When delivering a cube, it would be awesome if the game could automatically choose the direction for you when there's only 1 option. Possibly also automatically choosing your own track over an opponents (toggleable since that's technically not 100% correct, though probably 99.5% how it'd go). Then you'd only need to click when there were 2 opponents' tracks and not your own track, or 2 of your own track going toward different legal destinations.

4. For track building, you can just start clicking hexes, but for everything else you have to click a button... I don't mind the buttons, but why not just click a cube to deliver, a card to choose card, etc?

5. When building track, it might be smoother to put the "spin" button on top of the tile (where you choose the type), so you could just double or triple click to get it facing the right way. Even better would be if the game could make an educated guess as to which orientation to start (though that might be more work than it's worth). My opponent today did accidentally end his turn with track facing the wrong way, and it was turn 3 of the round, so the 4-tile track just disappeared (he lost a turn and $8k).

6. It's a little confusing when it says (for example) "sedjtroll must build track" at the top, when really I have other options

7. The Carcassonne implementation lets you zoom with some buttons on the screen. My opponent said he'd have liked that (I like the ctrl-scroll zoom).Also, he said Carc has a button that auto-zooms to show all the tiles currently on the board, and he thought that would be good here too

These are good but not the important ones now.
I think the best thing for the auction would be to have the option of having the start player rotate. Sometimes it
is necessary to make a small alteration of the rules to make it reasonably playable. The auction in turn mode
kills it. I have been against the auction in this series because it gives the advantage to the one with the most income.

I think the developer of Chicago Express also is working on a somewhat automated auction (not yet released) which is quite similar to the auction in railways of the world. Maybe you can cooperate so you dont have to do the same work twice. I think the idea is to set a max bid you are willing to make and when it is your turn again you will increase the bid with 1 until your set bidding roof is reached.

Bidding: Yes! That auto-bid scheme sounds perfect! See also the No Thanks implementation here on BGA, it does something similar.

Spinning tiles: Thank you! I think that'll make laying track smoother. I haven't seen it in action yet - does it show the tile where you click it in the same orientation as it will be placed?

Confirm incomplete track build: I think I replied to this in another thread... my suggestion is that when you click "done" after building, the game could check if the link is complete (it already checks links for completeness at the end of each round, and removes incomplete links, so it seems like that wouldn't be hard). If it's complete, no problem, continue. If it's NOT complete, the game could prompt the player with a simple "Link is incomplete. Are you sure? [yes] [no]" -- yes = continue, no = go back to where they can spin the tile (as if they had not clicked "done" yet)

OOH! Here's an idea... but I don't know if it's easy to do or not:

Suppose when building track, you clicked the space and it put a straight track there, then clicked it again and it switched to a curved track, then again and it switched to a rotated curved track... so you wouldn't have to go back up to the top at all, just click until it looks right, then click the next space!

When building 4 links, it's a little weird to click, scroll to the top and select the type of track (and maybe spin it), then scroll back down to click the next space, the ack up again... etc

Bidding in turn-based mode could have the autobid. Luckily "worst is first" option is there but I can see not everyone wants to use it.