Take a shot, or have her passport issued before you leave
The situation for Polish citizens who arrive in Poland while having a passport (and citizenship) of a third country (and not the Polish one) may be sometimes complicated. if the authorities required them to identify themselves and they are aware that this person is a Polish citizen, they are obliged by law to require Polish identification from them. There has been an issue where Polish-Canadian parents were travelling back to Canada with their 7-month old child and the child was denied to leave Poland, because it hasn't got a Polish passport (only the Canadian one). There was no problem on arrival, the issue was only on departure. The OP has prepared himself and his wife for that by travelling to Germany and then, to Poland. This might help. However, if you plan more frequent visits, it may reduce potential problems by having the passport issued.
Worst case scenario: Your wife will be denied boarding a plane in Poland during the border check, if one occurs in Poland, and not in Germany. This may happen when the flight to Canada will be in the same plane, and it will have just a mid-stop in Germany (Munich) for other passengers flying to Canada. If these flights are separate, you shouldn't have any problem, as the first one is in-Schengen flight. Please note that the border control officer would have to gain a suspicion that your wife is Polish and she is trying to leave Poland without proper travel document. It may sound unlikely (and I think it's unlikely), but you ask for the worst-case scenario. In that case, you should book a flight from Germany and travel from there.
Best case scenario: nobody would find out that your wife is Polish, except for her family (who already know that ;) ). You will travel as Canadian citizens according to general rules for Canadians travelling in the Schengen zone.
Source: Polish Consulate in Vancouver
- Your wife is a Polish citizen. Therfore, she cannot be denied entry to Poland, as Article 52.4 of the Polish Constitution states:
Obywatela polskiego nie można wydalić z kraju ani zakazać mu powrotu do kraju.
Polish citizen cannot be expelled from the country or be denied return to the country.
However, if she hasn't any document to prove that, it will take some time to verify that. You probably do not need that.
You plan to enter Schengen zone in Germany. This is a smart move if you want to try using her Canadian passport. I cannot find any regulation which forces a EU-citizen to enter EU/Schengen zone using EU-issued passport. Please note that there is no guarantee that she (or you) will be granted entry to Germany (and therefore Schengen zone).
You plan to travel from Germany to Poland and stay in Poland while legally admitted in the Schengen zone. Unless a situation occurs when she will be forced to present her identification to Polish authorities, there should not be any problem. However, please note that according to Polish Citizenship Act of 2009:
Obywatel polski posiadający równocześnie obywatelstwo innego państwa ma wobec Rzeczypospolitej Polskiej takie same prawa i
obowiązki jak osoba posiadająca wyłącznie obywatelstwo polskie.
Obywatel polski nie może wobec władz Rzeczypospolitej Polskiej powoływać się ze skutkiem prawnym na posiadane równocześnie
obywatelstwo innego państwa i na wynikające z niego prawa i obowiązki.
Polish citizen holding a citizenship of another country has the same rights and duties to the Republic of Poland as the person holding
Polish citizenship only.
Polish citizen cannot invoke with legal effect his/her citizenship of another country and any rights or duties resulting from that
citizenship against the authorities of the Republic of Poland.
Although both Germany and Poland are in the Schengen zone, there is a small chance that the border patrol may stop you when you are near the border (on both sides). Showing your Canadian passport with legal entry stamp to Schengen zone will suit you in Germany, and most likely in Poland too, however in the latter case that will not be legal. It is a violation of the law to use a foreign-issued identity document, if you are a Polish citizen.
I do not encourage you to travel without Polish passport or ID card (the latter can be issued in Poland only), but please remember during your stay, that there is no law requiring a Polish citizen to hold an ID document with himself/herself.
If you plan to fly to Munich, please note that you should also leave from outside of Poland. If your flight from Warsaw to Munich to Toronto is a combined flight, your wife may be denied exit from Poland as she will be a Polish citizen without valid travel document. These situations have happened before. If these flights are separate, you might get lucky.
If you want to keep your trip simple, smooth and you enjoy avoiding problems, get a passport :) You still have few months to go, that should be more than enough to have it issued.