My wife's English was not the best when we met but almost ten years later it's as good as it will ever be. She understands almost everything that is said to her and you have that perfect fall back using Google Translate if you need to explain something specific. 150,000 baht is less than £3500 so not the end of the world to a Brit. To a Thai it's a huge amount of money. I think I mentioned it before but my wife wife used her job as her only reason to return and she was successful in two 6 months visas and a two year visa. She had almost nothing to do with them apart from gathering the information.
You need to find out if she has been making payments to the credit card company and if she is paying more than the minimum each month so that the debt is going down.
I wish you luck. Meeting my wife back in 2015 was the best thing that ever happened to me. Ignore the naysayers. Too many on here who have been bitten before and want to tell the world about it and always assume the worst.