You should not take my teaching you a lesson over the Ukraine personally
I'm not calling you an idiot you're a smart creature but the statement about Austria was silly because:
Austria was the most powerful Germanic state at the time,
At the time Poland was more powerfull then all the Germanic states combined together, Austria was about as strong as a single Polish province, Poland had no business in letting third rate european powers run it.
if Poland allied itself with Austria at the time as an equal partner
Its like proposing USA ally itself with Nigeria as equal partners, Poland alone could and did excersize more leverage then any of its neighbours of any two of its neighbours combined.
Poland had absolutely nothing to gain from an alliance with Austria.
would have one foot in West European politics
In 1587 Poland had a huge number of political proxies and whenever it needed it just dictated various countries of HRE what to do, besides Poland at the time was still busily developing and colonising the East and the entire national effort was directed there, Germany was viewed as a poor, relatively barbaric (due to religious hassles) region and generally avoided as political grounds, there was no need or desire to expand into Germany and enough military and economic leverage/german proxy states to excersize any kind of policy.
and it would dominate central and eastern politics.
It dominated central and eastern politics anyway, you're basically postulating that Poland ally itself with a weak little country to gain something it already had without it.
No one in the region did anything without asking Poland, if Poland wasnt asked it was war and as noted Poland by that time did not lose a war for 247 years and it would be another 63 years before the collapse of polish power.
To sum it up Poland didnt dominate the eastern and central politics, it dominated the entire european politics, its immidiate neighbours were completely out of their league in every department and powers that potentially could compete like France or Spain were dependent on polish grain, salt, shipbuilding materials, cattle, meat etc.
If something was too far for Poland to beat the living crap out of it could still be ambargoed into submission so treating Austria as an equal is completely unrealistic, it was not Polands equal and had absolutely nothing to offer Poland on any level.
Too much German blood in their veins
Actually for centuries Germans chose Poland as their motherland over Germany, Duchy of Courland for example.