AXT is in a state of overcapacity, so what would be the point of "expansion via new property"? Share buybacks can indeed be mistakes, but not when 1) the money for the buyback is not borrowed, 2) the buyback is net, i.e. it doesn't merely neutralize share issuance, e.g. for executive options, and 3) the buyback occurs well below tangible book value. These conditions apply to AXT now.
The point is they might see the light at the end of the tunnel and might be eager to take out some shares at low prices. They are also increasing R/D so they obviously see some new opportunities (although they did not wish to expound on what those may be during the conference call).
I guess they wanted to give the stock price some support. The currency loss was what did them in and if the yen continues to weaken they will get hit there again. From what I recall they agree to a price in yen and get paid several months after the order, so AXTI takes the full currency risk. That bodes ill for Q1 earnings but in the end will wash out once the yen stabilizes.