The bot can stop playing arenas.
If instead of "Do not use queue" you select "Use queue"
When you add a task fot arena you can tell the bot to purchase up to a point of arena runs.

You can make custom card picking files, I think there's an example file in the externbot draft folder.
I'm pretty certain you can ban cards with that.

I don't know if you can make actual intelligent algorithms like make sure you have a good mana curve and especially couple cards with good synergy.

Imho the bot playing by itself isn't good for arena.
What I do is have the bot recommend me a round and make the play myself.

I use heartharena to "manually" draft my deck, it is pretty good at giving suggestions on synergies.

I'm not a developer but as far as I can tell the thing is.

1. No bot is as good as a decent human player,(edit) at least not with all types of decks.
2. There are both specific cards as well as deck archetypes that are exponentially harder for any bot to play.
3. Some cards are only good if you put them in certain deck archetypes, a small time buccaneer is broken in warrior and shaman but for a non weapon class it's useless.
4. This bot is not made for arena, it's made to farm gold, hero portraits and, for some decks, reach high ranks.

With that in mind you have to understand, the developers, already hard pressed as they are to maintain and optimize the bot for high ranking decks, can not give too much of their time to optimize a form of the game where you have no real knowledge of what type of deck you are going to end up with.
The bot can play an aggro or tempo warrior on arena, but if you draft a control oriented warrior, you are gonna have a bad time.

It makes much more sense to optimize the few archetypes the bot can play well in constructed mode.

The only way to make a bot capable of playing arena as good as a really good player, like an average of 6 wins is to make a behemoth A.I. that would possibly rival IBM's Watson.

Honestly arena is one of the few actually fun aspects of this game now that constructed is either aggro shaman/warrior or Reno decks.
Play it yourself if you want to gain extra gold cause as I said in point 1, no bot is as good as a decent human player.

And in the end, arena simply is not the focus of this bot.

Иди на хуй! Сам ты ребёнок! А ты провокатор ебаный и тролль!

You must understand. What are you doing, I would say excuse legni bot developer. What's so hard to make sure that the boat realized synergies cards? Complicated? then why not make a black list of cards, with which the bot can not work? This is not difficult after all.

I want to bot was better quality than it is now, but in fact I rests on the invisible wall even without developer and fanatics bot. Please do not be offended. It looks from the outside.

I've come to accept stupidity in Human being as it is not rare , actually it's quite common