I have Awakening on citra - and have run into similar issues. Basically, these codes edit the game's memory. And in the case of citra, unlike a 3ds, the memory changes place every time you boot up the software. Part of that code you are using - probably "0052D358" refers to the "address". It's where in the 3ds the particular data (in this case the character's exp) is kept. So for citra, you essentially need to find the new address, to apply the code.
Download cheatengine.
It looks something like this.
Load up citra and your game. Find out what EXP your character currently has (eg 86), and enter that number into the area in cheatengine that says "value". Press enter, which will scan your game's memory for that value, and a bunch of addresses will appear on the side. You want to narrow these down to the address you want. So get your character some exp in game. The address that changes should be the one relevant to that character's exp. Click on it, and press memory view. Keep that memory view window up and keep playing the game. Get your character some more exp and you should see some of the values in memory view changing (they will briefly be highlighted in red). You can then try entering different hex values in the area that was highlighted red. That should change your exp.
I've done this for items in awakening, and gotten a ton of second seals/master seals/dlc class changing items so I can reclass my characters early, and essentially have fun with different strategies. But you should be able to do this with EXP. In my cases, when I actually need to grind exp, I just use the DLC. Because working out the code addresses for every single character's exp and editing them is tedious, and a little difficult.
But memory view and cheatengine to mess around with items very easily. You can get stat boosting items and arms scrolls that boost your weapon profficiency. If you get a mage at level 6, you can boost their stats to max, give them arms scrolls and grind four levels to level 10 before promoting them. It's not that bad.
Hope that helped! If you figure out a better way of doing it, let me know. There are save editors online that you might have some success with.
EDIT -
gbatemp . net/threads/feftwiddler-fire-emblem-fates-save-editor.422439/ check this thing out. (remove the spaces) You'll have to find your save data, but you can do that pretty easily from citra.
