

1) No tech progress outside the Charis. Literally. The book is filled with Charisian-introduced innovations and new tech, but outside the Charis? Nothing. At best, other nations are trying to copy Charisian steam locomotives, of course with unimpressive results.
Considering that the whole idea of Charisian tech development was to encourage the others to do the same, the utter lack of interest to any non-Charisian tech development just seems to be... puzzling. We have quite a lot of text, describing how awesome Charisian new battleship, the "Thunderbolt", is. About the first Dohlaran Navy steam-powered warship, the "Arbalest" we knew only that this wooden-hulled ship suffered an unfortunate incident with coal combustion.
What is my problem with that? Well, my problem is, that the awesome "Thunderbolt" is absolutely not interesting to reader. We never doubted that Charis, with Owl's help, could design another new battleship with some improvements.
The modest "Arbalest" is the one which is actually interesting. Because she is the first really ingeniously designed steam warship ever build on Safehold. She wasn't calculated by mighty supercomputer using old Earth knowledge; she was completely designed and build by Dohlaran engineers & workers. She represent the litmus test; how efficiently the whole idea about "spreading innovation by example" is working, after all! It is really interesting to see, what solutions peoples, who does not have access to base of Terran Federation knowledge, would use.
But no, we didn't even get a look on her. Moreover, even when its mentioned that Dohlaran Navy is conducting joint exercises with Charisian, we never saw any one of Dohlaran warships.
Moreover, the previously mentioned non-Charisian technical ideas have a nasty habit of evaporating in TFT. The fantastic Dohlaran ironclad-killing rockets? Gone. Despite rocket artillery of different sizes being used quite extensively during the last stages of Holy War, there is no mention of any battlefield rockets in TFT, far less of heavy, coastal defense ones. I dare to predict that they would never make a reappearance later also, and any further rocketry would be another "marvelous Charisian innovation".
2) Bad guys are idiots. Or immoral. Or immoral idiots. It seems that the supply of capable men, not friendly to Charisians, was completely exhausted during the war.
The majority of bad guys of TFTare incompetent to literally laughable degree. With the exception of raping and plundering, they are completely unable to do anything right. All their planning and scheming are usually aimed toward "what other bad for us solution we could chose?". All their actions against good guys are the constant string of stupid faliures.
The blatant demonstration of bad guys stupidity, is when they saw the Charisian airship, they immediately dismiss it as harmless, because "it would be hard to fire rifles from airship". Here, I feel a strong urge to do a facepalm. I mean, really? The bad guys in question are Harchongians, which until very recently was pretty backward country, which military still relied on slings, bows and arrows. Which are ballistic weapons.
How is it possible, that no one of them ever thought about the possibility of airship DROPPING projectiles from altitude? Seriously, for peoples, well-aquitted with bows and slings, the idea of dropping projectiles from altitude would be... obvious. Not to mention that another obvious possibility - to drop explosives & incendiaries on bad guys-controlled towns. With all respect to "Safehold is not Earth", but I refuse to believe that flaming arrows and catapult-delivered incendiaries were completely absent from Safeholdian siege warfare.
3) Merlin is continues to cheat. Pretty expected, but, well, still unpleasant. He basically gave up all pretenses about working for the all humanity, and clearly worked only for Charis, supplying his beloved human toys with anything they asked. Geological data, so Charis could have as much gold as they wanted? Sure! Technical information? Just ask! High-tech espionage? Of course!
The problem is, that there are no vital reasons to do any of this. Charis is not under immediate threat, and have overwhelming tech advantage already over basically all other nations combined. The official justification is "to ensure the competition, to show the example for others", but it doesn't seems convincing - especially considering the utter lack of interest to other nations tech-development.
Must also point out, that I notice the example of goalpost moving in TFT. In previous books, the goal of Charisian innovative example was to spread the innovative thinking. In TFT, this goal is "suddenly" replaced with spreading industrialization. Which is NOT the same thing.
- spreading innovation - means encouraging others to adopt the inquisitive and explorative mindset, to study the world around and think how exactly it would work.
- spreading industrialization - means building factories & railroads by using Charisian-delivered technology. Nothing more.
And basically this switch of declared goals are symptomatic. As well as the obvious concentration of "all clever guys" in Charis shadow. The most blatant example is Dohlar - which was, during the war, the only one who could actually represent a challenge to Charis. In post-war era, the relations between two former rivals improved so much, that they are basically allies now. Despite all bad blood, all clear geopolitical questions with Charisians having a presence in the Gulf of Dohlar... All this is just ignored; all clever, innovative guys are in same boat now.
Conclusion: I sincerely hope that this little [s]screech[/s] speech would not be perceived as "you just didn't like the book, that's all!" (who am I trying to fool? This is exactly how my words will be perceived) I love the Safehold series. But - there are problems that concerned me, and, unfortunately, many of those problems became only more worrying from book to book...
Sincerely, Dilandu.