I have had this problem from the very beginning, being a first generation player I can attest to the difficulty of fighting ranged units. Musketeers and Witchdoctors are way to strong against close combat units. I've learned how to deal with Musketeers a bit more but it still doesn't change the fact that 99% of the time a ranged unit will not miss and it's even worse for the 100% accuracy of a skill. Up until Aquila I was able to solo the game for the most part until the Witchdoctors of Aquila made it virtually impossible for me to do so. For the first time I had to actually summon henchman to assist me against them and even then I've won more times by the skin of my teeth then I care for. The witchdoctors not only have the widest attack span but they're witch hunter skill stops any hope of an effective attack. Plus, their attack strength is utterly ridiculous.
I am a swashbuckler with a very high dodge rate and yet I never dodge a witchdoctors spell or musketeers bullet and on the off chance I do Jobas Ruse and Quick Adjust remedies that. Fighting a hoard of Satyrs is one of my most frustrating moments ever.
I implore you. Please do something about the severity of ranged units.
I don't think they are too strong, but by the time you get to Aquila you need to adjust your strategies to different enemies. For example Witchdoctors in Aquila also attack the 8 squares surrounding their target (like Old Scratch) therefore if you bunch you and your companions together they can hit 3 or 4 targets with a single spell. Therefore when you and your melee attack one of them make sure you are not adjacent to each other (e.g. using the four diagonals you can have four melee companions on a single enemy without the enemy being able to multi target).
Dont worry, think about all the max level swashbucklers you see in pvp! They've all done that, and it means you can too. If you haven't noticed, accuracy is terrible, and if you dodge them and their jobu's ruse activates, then they wont attack the whole group like they would if successful on their first attack, and you're likely to dodge again. Secondly, you can get alot of resistance (40ish at level 60) with a robe from the bazaar. Thirdly, and while this isn't as important, have old scratch and reset his epics so he has witch hunter 2. This is like a first strike or quick draw but for witchdoctors, and it also reduces their damage (around 30-50% roughly) so it's extremely good, especially as you're getting potential mojo echos. I'd go with Witch hunter 2 and mojo echo, not improved mojo blast 2 because he's going to trigger a whole group of witch hunters, then his attack will be so miniscule and his health so low it wont make a difference.
I was able to solo everything with my swashbuckler but did find the class harder to play then all of the other classes that I played. I don't think I'm that great of a swashbuckler player, always preferring ranged combat. I always buff first, and go into attack sometime after. With all that said, if I were to improve swashbucklers in the game I'd give them a group defense buff.