You are welcome. I thin though... I would have the ranger get their 2nd slot at level 4, double the level of a warlock (who gets their second slot at level 2). Perhaps I haven't understood how the spell-casting is halved?
Looking at the other half-spellcasters (ranger, paladin, artificer), the "half" part is calculated as such:
1st-2nd = 1st full spellcaster
3rd-4th = 2nd full spellcaster
5th-6th = 3rd full spellcaster
7th-8th = 4th full spellcaster
9th-10th = 5th full spellcaster
etc., with the caveat that except for the artificer, half-casters get their spells at 2nd level instead of 1st.
Along this model, the half-warlock would get its pact magic (level 1 warlock) at 2nd level, and would get its invocations (level 2 warlock) at 3rd level, and get 2nd level spell slot (level 3 warlock) at 5th level.
Looking back on the Artificer and its infusions however, I find my crafts (invocations) progression rather generous. I might address that.