I'm turned off by the majority of alchemy designs that are just absurd card advantage on a stick, but I think there are some diamonds in the rough, especially if you're willing to work for them. As it stands I'm probably running more in my cube than 99% of people already.
As you've pointed out some are more difficult to implement than others, and I actually think Seek is one of the harder mechanics to translate. You want to rephrase it to be like
Abundant Harvest, but that takes a lot of text. One day we'll get a main set mechanic that lets us shortcut this to something like "Discover a nonland card', but even then we'll need a wall of reminder text to try and explain it.
Since these started
less wordy, there's room to build the 'Seek' text into their descriptions. You could add a shuffle at the beginning or end but I don't think it's worth it.

I'm surprised you're so turned off by conjure, since it's pretty trivial if you just bring the corresponding things they conjure along. Like these cards really aren't too different.

I use clear outer sleeves, so I can just slip a 'Training Grounds' into the backside of
Trackhand Trainer during draft so the conjured card is there when they need it (and for them to see what the card does). You could always write out what it does too if you want to keep the cards separate, like I did on
Swarm Saboteur.
Here are some fun examples:






Chitinous Crawler I'm afraid might be a little too difficult without some dry erase tokens nearby. It would go hard with the new
Twilight Diviner though. See also the whole '
Emerald Collector' cycle, which I've seen work well in an un-powered environment that's into artifacts, but are a little too 'good-stuff' for me.
Boons are also easier side to track IMO, though I'd argue you need to create a token to go with them.




This also shows how you can more easily implement some 'perpetual' effects, since you could just tuck the tracker underneath the creature as a reminder.
Balance wise
Swiftspear's Teachings is actually pretty reasonable now since it's been nerfed to process OR haste, but you could run it whichever way you please to suit your power level.
The 'Starting Player' cards are also easy includes, though their designs are for the most part pretty uninspired. You could have a marker for this but IMO it's kinda unnecessary:



Surgical Metamorph is a 'fairer'
Phyrexian Metamorph in that you have to be playing blue, but it makes up for it since you can also copy planeswalkers and things.
Lastly it's worth mentioning the Alchemy re-balances. Mostly relevant for buffing my favorite tribe,
Ninjas.







These are all easy swaps for their regular counterparts. Though I've gotten feedback that it's hard to tell what's changed. I've made this more obvious on my copies but I ran out of images I can upload for this post.
Last misc. shoutout:

Which is made playable in paper by just adding 'Shuffle your library' to the start and exile 3 from the top.
There's even more in my maybe-list but I figure that's enough for now. If anyone else has tips for implementing some of these effects I would love to know! I know some people who have made spell-books work but that level of effort / complexity is where I think it's really not worth it.