Still haven't beat plantera yet, but I set up some heart statues & honey, and with Chloro gear & bullets, Holy Stormbow when Mothron showed up, the second eclipse went a lot better. Only got killed the few times she did the "sticking to you until you die" thing. Managed to get the sickle, shell, and Terra blade, woo!I'd definitely wait until I had access to the Lihzahrd Temple, Chlorophyte, and Lihzahrd traps with which to build a nice arena before worrying about Expert Hardmode Eclipses. Not coincidentally, that's also when you'll get access to Solar Tablets and Solar Tablet Fragments.
And I guess that's the answer to OP's question, isn't it? No, it's not too hard, if you're not able to beat something, you're just not using every advantage. There are definitely a few mechanics that feel (are) cheap, but you can do it!