Wow, converting D&D spells to DSA will prove very difficult. When I recently started playing DSA again after several years of abstinence and playing D&D (almost) exclusively, it was quite a culture shock.
Spellcasters in DSA are incredibly weak compared to spellcasters in D&D. Spellcasting is both expensive (in terms of 'astral points'; it can easily take a week to regenerate after casting a couple of spells) and slow (with very few exceptions they take at least several rounds to cast) and spells have an extremely short range to boot (a couple of metres).
I don't think there are even any spell effects that are the equivalent of 3rd level D&D spells.
What's really odd though is that e.g. summoning rituals are incredibly powerful compared to spells.
In my experience spellcasters in D&D are almost useless in combat unless the enemies cannot be harmed by mundane means. They do work quite well in the role of supporters, puzzle solvers, etc., though.
The Game System itself is quite nice and very detailed but it also gets very complex quickly. I found it almost impossible to create a character without the aid of spreadsheets. Here's a link, btw.:
HeroForge
To get back to your original problem:
I assume you currently have only got the basic set available? I'm asking because there's a 'Spell Compendium' available that contains about 200 different spells - very probably only in German though - the linked spreadsheets includes a complete listing. Maybe it's useful as a starting point.