Again - I don't know how Polish inflation protected securities work. In the US though - your only promise is a yield adjustment based upon a very specific CPI metric:
https://www.bls.gov/news.release/cpi.t01.htm
The metric changes definitions:
https://www.bls.gov/cpi/additional-reso ... hanges.htm
It also allows for substitutions in the basket of goods over time. It's a limited guaranteed, subject to relative valuations. The government has strong incentive to make low inflationary assumptions. More on the limitations of CPI:
https://www.investopedia.com/articles/0 ... eindex.asp
So while the inflation protected security will track predictably with the specific metric, I say there is still volatility. Especially if you convert units from the domestic currency to another measure of value - ounces of gold, or some other commodity.
With the US dollar being the global currency, we've been somewhat insulated from that. But I do not assume it will always hold true.