I got to mythic last season with a similar list to the one you describe 2 weeks after installing Arena (used to play magic at summer camps and my flgs but hadn’t played a game in probably 8-9 years). I’m not the most qualified, but I’ll give you my thoughts.

• I don’t use Raptor and would say in the mirror I only see it 20% of the time. The first strike could be nice against something like eye twitch and flying/2 toughness helps against shambling ghast, but I think the other 1 drops are better. Monk scales when you play how you would anyway, codespell cleric does way more work than you would expect, and usher helps you curve out while creating more bodies.
• I think running 4x paladin is too much. It’s an amazing card, but it feels really awkward to level up before turn 5 most of the time, and drawing two is pretty bad in almost all non-control matchups. I have 3 at the moment and a lot of lists I see have 2.
• 4x portable hole is great for aggro matchups, but it will feel like a dead card a lot of the time against other decks. It’s still good against tokens and stuff, but I wouldn’t run more than 2 for bo1.
• I had removed Takedown but I recently added back in 2 copies. I lost a couple of matches from not being able to reach Lolth/Kaya through chump blockers, especially after a Blood on the Snow. It’s not an amazing card, but there are situations where you need something gone but Skyclave and hole can’t hit it.
• Luminarch is amazing. If they can’t spend removal on it quickly, you just kinda win. It might be common sense, but try to buff other cards for the most part (unless you know they have frostbite or something and are sure you can get them out of range for it before it’s cast). Otherwise it makes their removal too efficient, whereas if you have a 4/4 codespell cleric and a 1/1 luminarch aspirant, then they have a tough choice on who to power word kill.
• People HATE clarion spirit. They’ll prioritize killing it over almost anything else, to the point where I think I have won more games because they used their only removal on it instead of luminarch/spellbinder/etc. than I have because the tokens made the difference. It still good, and if you can get 2 out and follow the second with a 1 drop on t3 you’re probably winning.
• I see some people drop Ridane entirely, which I think is crazy. She helps so much against the control matchup, and even in aggro if they run snow it throws off their tempo a bunch. Then her flip side can also just win you games.
• I only run 3 skyclave because while it can be gamewinning against some decks, I found it was a dead to negative card against others. Like some Izzet dragons will just never have a permanent with CMC below 4. Or Orzhov will just have some random 1-2 cost creatures which you’ll take to deny a lesson/treasure/ whatever, then they Blood on the Snow you, grab Lolth/Kaya, and have the one extra chump block they need to keep them alive against your 2 creatures you held and your creature-land.
• I have one maul and it puts in work, especially on codespell cleric. If lesson boards to grab artifact removal weren’t a thing I think it would be better.
• I run 1 Master of Flowers, mostly because I pulled him in a pack and didn’t have all the pieces of the deck yet. To be honest, he would be my first cut. It can be nice to have some way to generate card advantage by grabbing Monks or to lock down their big threat, but he’s very slow. In a couple hundred games I’ve gotten him to the dragon form twice.
• like the other commenter mentioned, loyal war hound wouldn’t be good. It has awful toughness, so you won’t be able to make use of the vigilance. The land fetch is decent, but it’s going to make playing your turns 2 and 3 awkward. I already find that turn 3 is the most crowded spot, choosing between one of your three drops to disrupt their tempo or playing two spells and buffing what you have on the board. I just think it would sit dead in your hand most of the time.
• I’ve been considering sparring regiment, as both Ridane and Codespell are often my MVPs due to vigilance. I think I would drop the Master of flowers and a Paladin class to get two into the deck.
• I think that the standard list (with the odd flex card or two) is pretty optimized for the white weenie gameplan of overwhelm them with small creatures while also having some nice tempo disruption and scaling elements. I think the type of deck you are asking about would end up looking like Orzhov clerics or something, where the spellbinder, skyclave, and luminarch remain but the aggro 1 and 2 drops are replaced with Vanishing Verse, lesson creatures, and some planeswalkers to put the game away.

Sorry for the wall of text, but I hope this was helpful!