What do you mean by respawning monsters?

The game or maps must have an objective
usally its by killing the boss and in some cases a second boss
if you cant clear the stage/map by killing the boss (objective) and the boss just keeps respawning i dont really see how youre supposed to progress in the game
if the game is indeed simmalar to Fire emblem games

Unless you meant its only the trash that are respawning
Then the question bcomes do they respawn after a set number of turns or do they respawn instantly?
If they respawn instantly i dont see how you can progress on a map withouth sacrficing some of the more unimportant characters
but if you do this on several maps this can become a problem later on because the characters you can recruit is limited
At least if it plays simmilar as Fire emblem.

There are for example "cave entrance" tiles and every turn a new enemy appears there if the tile isn't occupied. And yes there's always an objective. In fact finishing the objective is the easy part, the hard part is all the optional content that gives you characters, money and rare equipments WITHOUT clearing the objective.

If trash respawn at certain Tiles then i woud just try occupy those tiles myself with some characters
this way im blocking further spawning of trash
unless the game has some way of spawning the trash annyway or the game crash due to bug/error or its not actully possible to occupy those tiles

There are a few, such as:
the Riglord Saga series on the Sega Saturn (the first one was named Mystaria: the Realms of Lore, but after a few months renamed in the USA Blazing Heroes because of TSR and D&D I think),
Feda on SNES and its remake on Sega Saturn,
Wachenröder on Sega Saturn,
Black/Matrix on Sega Saturn, and its remake on Sega Dreamcast,
Valhollian on Sega Saturn,
the Farland Saga series on PC-98, DOS/V and Sega Saturn...

A pity, lots of them are japanese only, but for instance, Wachenröder has a script in english on Gamefaqs, IIRC.

Occupying the cell works as strategy, but then your have to continue with less party members and the characters you left behind can't be leveled. And if there is a sudden "back attack" event or anything, they are alone and most likely perma-die. Sometimes the spawn points are also in attack range of the boss so he'll start attacking you if you occupy them (which you don't want if you still want to reach optional goals before defeating the boss).

You cant use all the characters against the boss annyway and the characters you can select to use on the map are also limited.
Its been a long time since i played any fire emblem game but it was impossible to max all the characters in one playtrhough
especially since some of the characters you wont recruit untill later so if youre taking all the characters you can level
youre doing it wrong. You need to prioritize only a few characters that you will level each map and then keep rotating those you want to level the most
some of the more easy characters to level will be max leveled early on and be damage sponges.

If tiles are near the boss, then just chose some characters that soak up alot of damage.
Heck you can even place a healer nearby thats not possible for the boss to reach
This way you can have one tank or two to soak up damage and healer trhow some heals while you are hunting equpment or characters to recruit.
Dividing the characters inb to two teams or more can help achive this and then you can dicede when to go for the kill on the boss.

Back attacks are not really sudden, they are predictable the way they happen the same way at a speccific time
If you have played the map once and the character you wanted to level died to a back attack then you know when and where its going to happen.
Sure, some of the characters will die alot untill you learn what the game code will do for each map but thats just the nature of Fire emblem style games.

if you cant be bothered to trial and error your way trhough the game theres is probably a guide or Walkthrough
somewhere
But wheres the fun in that?

Well if you enjoy all that then by any means, get the game.

Would you say the Ogre Battle and Final Fantasy Tactics games are closer to Shining Force in gameplay or Fire Emblem with the permadeath and all the other things that have been listed?

I believe you are refering to Tactics Ogre instead of Ogre Battle (which is more a Strategy RPG than a Tactical one).
IIRC, Tactics Ogre and Final Fantasy Tactis do have a limited "permadeah" somehow (in TO, you cannot resurrect characters in most parts of the game, and in FFT, you have a limited time to resurrect each one at each time).

Can't say about Fell Seal, still haven't played it.
In another hand, IIRC, Telepath Tactics has been mentioned as a spiritual sequel too, but again, can't say more, sorry.

Yikes so Shining Force really is one of a kind. That's a shame.