I am unaware of any readable historical books about Poland or Hungary. You may be better off with historical novels, as suggested by Rustymusket. I highly recommend the historical novels written by Henryk Sienkiewicz for Polish history: "With Fire and Sword," "The Deluge," "Fire in the Steppe," and "The Teutonic Knights." Very romanticized pro-Polish writer (also wrote Quo Vadis), but he gets the broad outlines of the history right. I am sure that a search for nationalistic Hungarian writers would give you an idea about what is out there. Also, any book about/including Janos Hunyadi would give you an idea about early Renaissance Hungary. I always thought that he was pretty impressive; guarded Hungary from the Ottomans and put his son on the throne. I believe that bells are rung at noon in Christian churches to commemorate one of his victories over the Ottomans. He ended up dying of plague or cholera.
Polish history would be very different had its ruling family not died-out. The result was an elected monarchy which was a national nightmare. Bordering countries tried to influence the elections by passing-out gold and titles to Polish magnates. The magnates extracted additional rights against the crown in return for their votes. It always struck me as a Papal election on steroids. They had some good elected Kings but also ended-up with the Catholic wing of the Swedish Vasa ruling family that resulted in very destructive wars between Poland and Sweden. The magnate families had vast wealth and power. They owned property as large as some European kingdoms which they ruled with almost absolute power. A single noble in the Polish parliament could delay any act by simply objecting. I always considered it amazing that Poland lasted so long as a thriving country.
The history of Poland is fascinating and can lead to finding interesting connections with other countries' history. A Polish magnate put his son on the Russian throne after invading and capturing Moscow. That act added to the desire by the Russian nobles to end the "Time of Troubles" that lead to the placing of the first Romanov on the Russian throne. Prussia was a vassal of the Polish crown, however, when the Polish king needed support from Prussia/Brandenburg, the Elector negotiated independence. That Elector was great grandfather of Fredrick the Great, who took part in the Polish partitions.
If you can locate a copy in a language you read, I suggest you may try the commentaries written by Jan Długosz, who was secretary to the Bishop of Krakow in the 15th Century. I have seen his commentaries referenced in several histories about Polish subjects, however, I have not found an English translation yet. If you can find a copy, I assume that it would be a treasure trove of Polish and European history from a first hand source.
experiments at 11x.