Firstly the pronunciation suggestion is fine.
Fine? How’s so? It’s an approximation at best.
Secondly, I notice you don't offer any alternative.
Why should I? To confuse the poor soul even more? There’s no way to do this phonetically in English, not make it sound silly in the process that is. Best way is to listen to a native and repeat it; otherwise you will always mispronounce words. As some have already suggested, if you don’t have the native to pronounce it for you, use an online synthesizer program, a lot closer than your approximate suggestion. Hat off for trying though.
PS. This was not a dig at you so there’s no need to be anal about it, simply pointing out the obvious fault in trying to do so. FFS man if you’re such a purist in regards to English language then the least you can do is to be consistent. Stop trying to do the impossible and stop being a butcher in regards to Polish.