@NotMyWallet
I will try to tackle as many points as possible (that affect the spawns themselves as I was the one to make them). However, the only one that can answer regarding event chances is Walross.
Bold Eevee can be used in:
-Vaporeon (great for PvE and PvP content, even if there are better options)
-Sylveon (same as above)
-Umbreon (amazing PvP pokemon and specially for PvE content as it's an excellent wish passer)
-(if you're willing to, Espeon instead of Timid and Glaceon too, considering Espeon can be Bold as a defensive anti hazards lead and Glaceon has base 110 def and is SPATK based, even though it's terrible deffensively due to its Ice Typing, but I don't judge player choices).
This spawn was included as Eevee is an incredibly sought after pokemon with multiple evolutions using Bold for different purposes, and it works perfectly for them.
If you are not satisfied, you are always welcome to make a Spawn Change suggestion. I look at them as frequently as I can (even if we barely get new suggestions and I rely more on player's opinions).
No, it might've resulted in you not getting anything either. It's purely up to RNG. You obtained multiple event forms and shinies (4 shinies and over 10 event forms) while in my player account I only got a Mild garbage Slowpoke and an accidental Halloween trash Gastly in a random map in Sevii Islands. Yes, my luck was so insanely bad that the only way I got an event form was because Walross decided to implement Halloween Event spawns during this event (which I am grateful for, 5 PvE coins! that's stonks to me.)
A pokemon does not have to be absolutely godly in PvP and PvE to be worthy of a spawn. By following that logic, pokemon like Slugma, Spoink, Unown, Girafarig, Carnivine and other pokemon would never get spawns and never be huntable. I tried to fit as many good things as I could between both PvE + PvP + mixing in all possible Valentine Forms in spawns, to the point where they were absurdly overpowered in every single spawn (even Walross scolded me for this, which I agree with, I went a bit too far). A pokemon does not have to be super strong to deserve to exist. Not everything is based around PvP usability. There's fun pokemon to use in PvE too. Pokemon are not forced to only exist to beat other players and increase your rating. It's a MMORPG with a gigantic PvE side content, it's not a PvP simulator. It was no attempt to balance it with Alakazam, I just found Chingling cute and I fit it there. I was not even going to put Houndour in, yet I ended up doing it (even though I didn't believe it fit in). The map contains Clefairy, Slowpoke, Poliwag, Marill, Lotad, Shuckle, Eevee aside from Chingling. How is this a bad spawn? Can you argue why?
Skipping over Valentine chances (which I cannot argue about, as I do not act on them) it is up to your luck. There's no statistical diference, you could've found the same event forms in front or in the back, you could've found none or 30 in a day. It's simply luck unfortunately, and there's nothing else I can really tell you. All event forms don't have to be magically gifted to everyone just because it's an event. I personally liked the Chess minigame but I disagreed on gifting out Valentine Ralts to the winners on a chance because I felt it devalued it and it no longer made it rare. And there's nothing wrong with having rare forms that you might not be able to find in events.
Some players are lucky, some are not. Both for event forms and for godly IV, natures, abilities, and so on. I've lost millions on multiple pokemon just due to a nature or IV fail, but I will still keep hunting. It is sad but RNG is unfair and luck is luck. There's nothing we can really support you with. Spawns are not worthless because a player cannot find an event form. Nobody is taunting you. You yourself admit that if you had found a rare form or shiny you wouldn't be complaining.
The event will still continue for some days. You might be lucky if you keep hunting and eventually find your Shuckle. I wish you the best of luck!
Do not overwork yourself. This is a videogame, you're supposed to have fun. Don't burn yourself out just for an event form. It's a game, it's to be enjoyed, there's obviously going to be frustrating parts but a videogame is there to be entertained by and spend your time enjoying it with friends and whoever you'd like to share it with.
Kind regards,
Kvar