There were several JavaScript errors in the first Solitaire version. However the errors were fixed during time and I don't remember any flaw in the past about two months when I play Solitaire. No software is bug free but current version is pretty stable, I think.

If you have a problem with Solitaire, can you post its description, please?

With respect to house edge, remember that it's a game of skill. It's common that when you overlook a single card you should play with, this overlook can determine the outcome of the entire game. In practice, the real house edge is dependent how carefull your game-play is. In case you stop doing mistakes, house edge is low.

Anyway, in our development plan, we have a note about Solitaire. We consider to make Solitaire more tolerant to player's mistakes - to allow infinitive going around deck. This would have a big impact on payouts, because it minimizes impact of player's mistakes.