New Game Plus is supposed to be very challenging, as it is the only way to unlock the true ending, and truly "beat" the game. I do feel like you might be struggling more because of a lack of knowledge of mechanics and tricks than actual difficulty though. Some interactions are obvious, others, not so much. Using Ebb/Flow is very important to a Magic user, properly utilizing status effects makes tough fights much more manageable, and so on. The manual should help you understand how different skills and statuses work.
Most skill mechanics, such as Eb and Flow, are explained in the manual. Simply put, some Magic spells place Ebb stacks, some place Flow stacks. If a skill that places Ebb stacks is used against an enemy with a Flow stack, it will deal bonus damage, and if a skill that places Flow stacks is used against an enemy with an Ebb stack, it'll deal bonus damage as well. Some skills modify Ebb/Flow, such as Charged Trickle (Adds BOTH Ebb and Flow to all enemies) and Fizzle (Turns Ebb stacks into Flow stacks and vice versa). Using Ebb and Flow correctly is key to playing a Magic based character, as it is a potential 50% damage increase.
As for the game being fun or not, that is completely subjective. I personally find easy games incredibly boring as I look for a challenge rather than a story. If I want just a story I'll go read a book. Everyone has their own idea of fun. Also please note that there is no Easy difficulty. There is Casual, Normal and Hardcore. Nowhere does it say Easy.
The Buzzy Sword can be gained by giving Craft Kits to the weapon smith in town. If you have the Elemental Sword you should also have the Buzzy Sword available. You can swap freely in town between already unlocked gear.
As for other hints... The Flamelord splits its damage evenly between Magic, Brawl and Tech, and because of this all stat builds are equally as effective as him. Worst Candles, however, deal exclusively Brawl damage. Meat lowers their damage output by a lot. Dex also helps protect against it. Getting the Brawl skill Hidey Pose and one of its upgrades will help you greatly in almost every fight in the game. The same can be said for the Magic skill Invigorating Trickle. Overall I'd try to debuff the Flamelord as much as possible with Stuns and other stat reducing effects while using self-heals and tanking the bombs. Try to sneak in some damage against the Flamelord when possible as well. If you are full Magic, chances are you can kill Worst Candles in a couple of turns while still dealing damage to the Flamelord.
No one's accusing you of being a quitter. I made Celia's Quest intending to make a very challenging game that would force players to think in different ways than they'd do playing a normal RPG. Many players struggle with the game at first, and then again when they start New Game Plus, as New Game Plus removes several of the crutches that keep non-optimal setups alive during a normal playthrough.