For starters, there is no such thing as "European cuisine." Different groups had their own culinary practices: those in northern France did not eat the same food as in southern France (not even considering the differences from Britain to Germany), the rich did not eat the same food as the poor... and so on and so forth, so the reformation impacted different groups in different ways.

That aside, though, yes, food practices did change somewhat after the reformation, though Individual devotion to fast practices ultimately ran much deeper than blind adherence, and many people continued to fast as a part of a belief in spiritual cleansing, which mitigated the extent of the culinary changes. However, food and food laws were a catalyst for the reformation, and an important way that people understood changing times, though changing ideology did not enact widespread changes in dietary practice overnight, with some exceptions where climate and local foodways made all parts of the fasting diet extremely difficult to maintain.

To answer your main question as best as can, fish was much more expensive than meat during fasting times in post-reformation Catholic Munich. I suspect the reverse would also be true, though I didn't find any sources that speak to that directly (EDIT: as in, in Protestant areas, fish would not be any more expensive or would be less expensive than meat. higher prices for fish seems to apply, post reformation, to catholic areas). An economic historian might be better able to speak to that.

To consider the larger theological picture regarding food and the reformation, food was a major catalyst in several events of the reformation, though the attitudes of reformers did not neccessarily reflect a deep seated dislike of fasting practices by most of the peasantry.

During The Affair of the Sausage, Christoph Froschauer, a printer, consumed sausages during lent without purchasing a dispensation (pay to violate church rules, basically). He was charged, and Uther Zwingli (who was present but did not partake in the consumption of the sausages) preached on their behalf in Von Erkiesen und Freiheit der Speisen (Regarding the Choice and Freedom of Foods), which argued that fasting should be voluntary. This disagreement helped begin the Swiss reformation.

Likewise, Elaine Khosrova argues that dairy production and dairy consumption was also a major catalyst for the reformation. Butter wasn't eaten much in Rome (fish and non-animal oils, both acceptable during fast days, which made up nearly half of the calendar were much more common in southern Europe), so the church's inclusion of dairy and meat in fasting laws (fast days made up as many as 150 calendar days) blocked off several northern dietary staples, which the rich could buy their way out of. These dietary laws about butter and animal products were loosened in 1491, prior to the reformation, and enabled the increased importance of butter and dairy in food. These rules were more disruptive than rules surrounding meat consumption, as butter was much more important for peasants than meat, though these changes predate the reformation. While the changing rules of the Catholic church enabled changing dietary habits, the rules also demonstrating how arbitrary the church's rules and regulations had become and provided fuel for reformers. As butter was more materially important to most people than sausages, this change impacted culinary practices far more.

In another example, the colloquy of Erasmus contains a dialogue between a butcher and a fishmonger exploring the impacts of dietary laws (prices, demand, etc) and ultimately condemning the church's dietary laws as arbitrary, but it stops short of embracing the reformation and instead focuses on encouraging the Church to change its rules.

Reformers argued that church fasting requirements are not biblically sanctioned. Instead, the Catholic church, which ignored the dietary laws of the old testament, had essentially created its own elaborate infrastructure of dietary laws with, according to the reformers, tenuous scriptural precedence. While the rules might've been arbitrary, however, they were definitely important to people and widely accepted by parishioners. In some ways, the reformation didn't so much eliminate the catholic food practices that had made fish a much more important part of diets, but transformed it from a requirement to a belief that fasting could be an important and spiritually cleansing action, encouraging a more balanced diet throughout the year instead of the cycles of fasting/feasting and consumption of regionally inappropriate foods. Those fasting/feasting cycles, which the reformation took aim at, had actually helped create the food culture of medieval Europe (as much as you can say that there was a food culture of medieval Europe) by encouraging types of decadence not encouraged by reformation churches. These changes in some ways reinforced the premise of fasting, but loosened the rules in ways than enabled for more diverse but still rather plain diets, though the reformation changed European foodways much less than the advent of the Church's introduction of elaborate sumptuary laws.

On the whole-- yes, I'd imagine that is somewhat accurate, and the change of the church's rules enabled the peasantry to eat more butter eggs, and dairy, though these changes predate the reformation. The reformation mostly enabled a less punitive, rules based type of fasting, but also eliminated the cycle of fasting and feasting that had generated so much culinary change in medieval Europe. I hope this makes sense!

For a great book on this subject, I suggest Ken Albala's Food and Faith in Christian Culture

There's also an interesting chapter in "A History fo Cookbooks: From Kitchen to Page Over Seven Centuries"

Some other sources:

"Fasting, Piety, and Political Anxiety among French Reformed Protestants"

and Butter, a Rich History