As far as the modes you are playing, you are fine. You should play what you find fun regardless.
With respect to resource management:
The most important aspect to realize is that traitstones are largely a closed system. Every traitstone type except celestial is used only to trait troops or craft other traitstones, and celestial is crafted only from non-traitstones. Therefore, the only thing that matters at any given time with respect to traiting troops is whatever your bottleneck is, the type or rarity that you happen to be missing at the time. If you have 900 of every runic but no minors, those runics are useless to you now and forever. But your long term bottleneck might not be readily apparent.
I’ve done the math on this a few times based on how many stones of each type are needed to “finish” traiting (including projections for new troops). Minors might bottleneck you if you are in a fast guild and focus on explore a lot but don’t get a lot of tributes for gold keys, Runics might bottleneck you if you are in a slow guild and play at a more casual pace, Arcanes can bottleneck you just because you don’t happen to have the right type on hand at the moment (unless you explore a lot, a great majority of Arcanes will come from the glory troop packs week to week), and Celestials can bottleneck you if you don’t buy the Sunday 50 gem offer in the dungeon and craft too many troops/weapons in soulforge. If you are within the bulk of the “normal” playerbase, your bottlenekcs will shift back and forth between minor/runic/arcanes (sometimes celestial, but usually only if you craft them away), so crafting away any of these has potential to cost you time long term.
With majors, though, you get so many majors with respect to how many are ever needed, you should never craft into those, but its okay to craft some of them away. As long as your major stone count stays within about half of what your minor stone count is for a given color, you should be ok. However, even though 200 souls is “faster” to farm than a runic, you can generally get 3 random stones in the time it takes to do one soul-farming battle. If you have to soul farm excessively to fuel traitstone conversions habits, you are probably still extending your overall grind, because you could just use that time to explore faster toward your next arcane bottleneck, and those will bottleneck you unless you are in tons of legendary task per week guild or massively overbuy glory packs (and even then, you’ll probably have one or two types that are almost always out). You can wisdom orb to get past some of these, but orbs are most efficiently used on 3rd mythic traits (24 arcanes saved) then 2nd mythic traits (18 arcanes saved), with legendary second traits being a pretty distant third (10 arcanes saved).
Wasting some majors to craft to runic should otherwise be fine, since my numbers show you’ll only use about 50-66% of those that you obtain, ever, so as long as you don’t completely run yourself into the ground. But crafting traitstones in any other circumstance generally cost-negative long term, because it takes much longer to get those stones back and then has a soul tax associated which is another time cost. It is much faster to farm 1 runic with an optimal explore team than it is to farm, for example, the 21 minor and 700 souls that are needed to make 7 majors and 200 additional souls to craft the single runic, and doing this too often would result in you needing to go back and farm those when your bottleneck shifts to needing the minors or souls, and farming the minors and souls cost much more time than just getting the runic (about 3-4 times as long, roughly, in explore).
Again, the bottleneck is what matters here. If you manage to keep your bottleneck on the same stone type forever without ever needing to craft a stone have ever crafted away, and avoided any significant soul farming/arcane gathering opportunity cost, you have successfully navigated and min/maxed the system. If you ever have to go out of your way to acquire a stone that you have previously crafted away, you just deferred and extended part of your grind.
Everyone elses cautions about using the soulforge to craft stones were likely about this as well.
With respect to traiting stuff, this is a matter of preference, but if you don’t “need” it (either for kingdom star progression or because the trait is significant and you actually intend to use the troop), you can just avoid traiting it. For me, this includes nearly every siegebreaker troop/godslayer troop on all of my alts, since epic troops are overly costly in terms of power, particularly for something you never use again. This lets you have more options open at any given time when a good troop drops that you do want to use (eg., any empowered converter), and you don’t have to go farm explore for hours or use costly soulforge to be able to have it at max strength immediately. That way you can farm proactively and only pull the trigger on traiting (and also leveling) troops only when it will upgrade kingdom stars. Troops you aren’t using and aren’t contributing kingdom power don’t need resources committed to them.
My findings over thousands of explore battles were about 1 in 17. On the Dev Q/A stream, they stated a different slightly lower drop rate (I believe 5.5%?, which would be about 1 in 18). Either way, thats an average of 10 per hour in explore… yes, you are going to streak, but it isn’t that bad long term. Also honestly, you get so many arcanes spread throughout the game that if you use them sparingly, you don’t need to craft them and you barely need to explore unless you are at a point where you are just trying to accelerate specific kingdom stars. Consider the cost to craft - 6 runic, 2 celestial, 400 souls. Celestial I’ve estimated at about a third of the drop rate of any given arcane, so if you ever use so many celestials that they happen to bottleneck you, you just multiplied the amount of time you needed to farm by six, from about 6 minute to about 36 minutes for two celestial. Crafting celestial themselves is now also a worse deal than it has ever been, since you need these jewels to craft old event weapons, which in turn makes Arcane a worse deal than ever.