Yes so i am mostly low on gold in this game and nobody wrote how to properly earn gold in the game.
I also see you get TP in this game and you can trade it in the adventurer's guild for some items, which there is nowhere a list how much what costs when selling it for gold, it is just the TP cost in the adventurer's guild for the items.
And i don't even know how much TP is possible in a single playthrough.
I know you can earn titles and earn some gold and items also.

Also just reached a boss i can't beat yet called Leptocephalus.
All of the battles before were kinda not hard but this i think i am underleveled and i need more better gear to upgrade and use my PP points.

I was testing some things and marfile seeds costs 45TP and you can sell them for 15000 gold so that is a way to do it.
Edit: Beat the boss Leptocephalus needed more magic resistance to beat him and was level 12 with Sieghart and better upgraded equipment. Needing to grind was probably 1 or 2 hours until i could beat him. Some characters were level 11.
Now this is a different mechanic think that each time an ally falls you get sp to all the characters standing which i then used their special to finish the boss, but didn't reach overkill.