With the new Crown System, and spending hours at it, it seems I'll need 100 years to reach Level 5.
My Spanish tree has 500 lessons in 108 skills. (I'm testing the new Spanish tree, so you may have fewer lessons and skills in your Spanish course.) If a skill that has N lessons takes N x 12 finished lessons to get 5 crowns for that skill, then the entire tree would take 500 * 12 = 6000 finished lessons.
At 6 lessons per day, it would take 6000/6 = 1000 days, or a little less than 3 years, to get all 108 * 5 = 540 crowns starting from nothing.
Since you are already at level 23 in Spanish, you probably already have 200 or so crowns, so it will take less. If you're at level 2 for everything, and have 108 * 2 = 216 crowns, you already have credit for 500 * 2 = 1000 finished lessons, so it would take about 1000/6 = 167 days = 5.4 months less.
It's by design that it takes so long to get all the crowns. Since you're at level 23 now, you've probably been in a boring rut of review for quite a while. Now you have a new long-term challenge.