Cheers man,
have you checked out the ranges from GTO-wizard? They are constructed for 50nl
They are free btw

Zenith has high rake sims

Thank you for your suggestion, I didn't think about gto wizard so it will definitely be very useful. I see it has a section for 50NL with "Pokerstars rake"; I guess it's referring to non-eu PS rake (so 5,0% with 4bb cap rather than the 5,5% with 6bb cap that I usually play on) but that should be close enough for my purposes.
I've checked Zenith but their sims are not suitable for my (even higher) rake structure.
Thank you guys, you've been very helpful.

for I might have fun limping from SB but losing 60bb/100 from that position is not equally fun :P.

This statement is very concerning. You would lose at 50bb/100 if you simply folded every time you are in the SB. If you true winrate is -60bb/100, there is a serious problem since you are doing worse than folding. Assume you are in the CO. What is your winrate if you fold? It's Zero. Folding is zero ev. Now, you look at all of your hands and you see that you are raising hands that are losing money. Losing is worse than zero, so I would cut out all of the losing combos (assuming sample is big enough, which it certainly is not). Run Good/Run Bad can have a huge impact on small samples.

On to simple adjustments:

I would stop limping completely in the short term.

Focus on winning pots preflop (we do this by 3 betting better, raising 1st in better and stealing better).

Most preflop ranges are fairly similar. 16-20% UTG, 18-24% MP, 25-30 CO, 43-50% BTN, 43-50% SB. As you are learning, basically you just tighten up some from every position. I would focus on playing tighter from UTG/MP since they simply call too much In Position and conversely, they don't 3 bet enough. No one is going to catch on that you are opening 12-14% UTG or 13-15% in MP. I would start to loosen up from CO/BTN/SB when you have a chance to raise first in.

I would cut out calling opens IP (i.e. utg raises and you have 54s on the btn). I would just fold until you start to expand your knowledge. Or you can 3b but I would mostly eliminate that for now.

For now, I would use 66+, All Suited Aces, All suited Broadways, AQo, AKo and KQo from UTG and then add in like AJo/ATo and maybe mix 55/44 like 1/2 RFI and 1/2 Fold. Very simple to follow and if you filter your database for that specific range when you RFI UTG, you will see just how well you do with that range. As you improve, you can start adding more combos in slowly as you approach a more "standard" chart based RFI approach.

Well Hawks, thank you so much for this very in-depth comment. I'm slowly learning how to adjust to my rake structure, and I gotta say, following preflop sims after watching so much poker live and online (but with softer rake structures) requires a lot of discipline not gonna lie :P. I guess my issue with the SB position winrate came from overcalling too much, hoping that seeing a flop with 1 or 2 recreationals involved would compensate for the awkwardness of being first to act in a multiway pot. I'm starting to get rid of this bad habit, overcalling less from BB too (I used to have 30-23 of VPIP-PFR, but I'm beginning to realize that at this rake structure that's not doable).