I've been using D&D Beyond off and on for awhile, but have stayed away from using the sheets until just recently because a few of our simpler house rules clash with the character creator and the sheets. Because of this, one of the things I would like to see is the ability to choose to use spell points, instead of slots, on the sheet since that is a rule that is written for use in the DMG. 

Another thing I would like to see is the ability to add spells to a character from any spell list. Maybe a DM has a house rule that players can learn a cantrip, but for some classes, this would require "homebrewing" quite a lot to allow this to function in the character sheet. 

Both of these seem like simple things that would open up the character sheets to more players and games. 

I know spell points is something they want to get to some day, but I'm guessing it will be a while.

In terms of adding spells, depending on the specifics, there are several options.  They do require homebrewing, but some of them are pretty simple homebrew options:

-for adding a cantrip, you can create a magic item or a feat that grants the cantrip.  If using a magic item, just make sure the "requires attunement" box is unchecked.  If using a feat, you could use the Magic Initiate feat as a template and adapt as necessary.

-If you want to add a spell to a class/subclasses spell list, that is also an easy homebrew to do: make a copy of the spell in question, change the name for clarity's sake, and add the relevant classes to the "available to classes" box.

I agree it would be nice to add spells outside of RAW from the character sheet like you can feats and the like, though.

If the two examples I gave of workarounds won't do what you need, if you tell us more about what you need to do, we may be able to help you find fairly easy ways to do it.

I did attempt a work around by creating copies of the spells and adding additional classes to the spell, but that unfortunately doesn’t solve the problem if the spell in question is a cantrip and you’re adding the spell to a class like Paladin that do not use cantrips. While the spells do appear in the known spells list, you are unable to “prepare” or “learn” them so their usability on the sheet isn’t there like the other spells.

While the item way would also work, it becomes rather cumbersome the more spells that you have to do. At that point, it would be much faster to keep track of spells outside of the sheet here, which to me defeats the purpose of using D&D Beyond entirely.

Quote from RiverFang13 >>

I did attempt a work around by creating copies of the spells and adding additional classes to the spell, but that unfortunately doesn’t solve the problem if the spell in question is a cantrip and you’re adding the spell to a class like Paladin that do not use cantrips. While the spells do appear in the known spells list, you are unable to “prepare” or “learn” them so their usability on the sheet isn’t there like the other spells.

While the item way would also work, it becomes rather cumbersome the more spells that you have to do. At that point, it would be much faster to keep track of spells outside of the sheet here, which to me defeats the purpose of using D&D Beyond entirely.

 Notice that I specifically said that for cantrips, you add them by a feat or a magic item.  This is absolutely essential for characters who don't have cantrips as part of their spellcasting ability.  You can actually just homebrew the cantrip to add to the available to classes section for casters that do generally get cantrips:  unless you want to increase the number of cantrips a character can cast; then you have to go the feat or item route.

It may be that your table has homebrew rules that just can't be accommodated here (yet).   But if you want to try to make it work, there are a number of us who would be willing to help you figure it out.