Hi faerygirl, unfortunately, you won't be reimbursed for lost gems used to complete levels. The reason I'm so familiar with this is that every time I log into play Cookie Connect I start at Level 784. It doesn't matter how far I progress - I actually closed out Level 800 and received the "Level 800" badge to prove it - every time I log out then log back it I find that all my progress is lost and I'm back at 784. I spent a lot of gems to finish through Level 800 and it was made quite clear to me that EA has no way of verifying how many gems you used during the course of any game play. At least the customer service representatives don't and they absolutely will never believe you used any gems at all in the course of play.
Your best bet is to maintain a tight reign over the number of power ups you use and to clear your cache frequently to avoid freeze ups. They do occur in Cookie Connect - it happens to me at least once an extended session - and it sucks to see not only your hard work but also your hard earned money seemingly thrown down the drain. You can't sue, and since this sounds like a one-time event you're specifically referencing EA does not accept responsibility for your financial investment since the reason for freezing could be many, many different technical reasons unrelated to their servers or systems.
Again, clear cache regularly while playing Cookie Connect and avoid extended sessions without doing so. That's you're only solution. Trust me, I'm saving you hours of frustration attempting to recoup losses.
