Have to agree with Lechen being stronger then a fair wack of the gatcha girls.
But then the girls have never been balanced to be honest.
Toad Lilly is basically a 6* without the full atk, her defensive stats are actually higher then most 6*s right now.

As for getting flower gems... for FTP peeps they do come fairly often, about enough to do a 50 pull every 4-5 weeks.
That in itself is not terrible considering the price if you buy them.

All event girls are worse than non event 5* girls. Even Edeweiss has a flaw: her skill activation is 23% at lvl 5. This is inferior to many 5* girls at lvl 1.
In fact all girls with good stats (Edeweis, Lachenaltia and Lavender) have bad skill activation (23%), while the girls with lower stats has 30% activation.
When a non event girl has lower stats than a event girl, look at the skill activation and buffs to see where she overcomes them.