I've only played SoSC out of those (and played Elminage Gothic for 3 minutes till the guy in the training center asked me if I wanted to train and murdered my party which made the game look like I Wanne Be The Guy the RPG) and to me it looked like you have to grind a lot. You meet some enemies you must not fight and you learn it because they oneshot some of your guys. Then they go to revive (and probably afterwards revive) and all that time you have to fight with backup guys, thus you can't really progress because you're asking for another oneshot with weakened party. Maybe it becomes easier later but it's not like the game was hard, it just could force you to lose a guy for couple of dozen fights.
Elminage is not SoSC, you don't loose hearts, you don't really need backup guys - unless you're playing Ironman or hate save abuse or something. You should have a backup Alchemist (to enchant items) and Bishop (to Identify low quality items for free... otherwise identification will be very expensive), if they are not in your "core" party, but they can never leave the town.
The training guy isn't that tough, only has AC that's difficult to hit for a starter party. Still, if you manage to disable him with spells (sleep for example), he's a sitting duck. But he's probably not intended to train novice parties. It's much easier to just go trough the first dungeon. He's very useful to quickly bring new or multiclassed characters up to speed - to level 6 or so.
You team them up with one other character, who butchers the training guy in 1-2 rounds for easy xp.
And you don't really meet many enemies you should avoid, at least before the final, third, post-game dungeon. There StarGazers or the like can really spoil your day. Oh, there are also the so called "Floor Masters", bosses, who roam the last floor of each dungeon. Early on you should generally avoid those guys too. You can sometimes cheese them with Charm so they perform Seppuku, but its not advised. Later on you might be able to steal their equipment and/or they can serve you as excellent summons.
Enemies have deadly abilities later on, but it's generally possible to counter their abilities. For example the RedCaps from the Great Tree have a high-ish behead chance and come in packs. But their accuracy sucks, so if your front liners have decent armor and maybe you cast the cleric AC boosting spell once or twice, they are almost unable to hit you.
Early Lizardman have spears, with M-range, so they can instagib your squishy backrow characters. But you can have your frontmen defend the most vulnerable/important ones.
I guess the poison-breathing enemies from the basement of the Great Tree could initially be a problem, as you need decent HP to survive them. But you can visit other locations, level up a bit and come back.
In general it is very important to prioritize threats and focus fire the most dangerous and/or squishy enemies. That is also the reason offense-heavy parties are much superior to defensive ones IMO. Both you and your enemies have access to deadly abilities... its much safer to eliminate the big threats first then hope you'll pass the behead/instant death save.