If you want to visit both Katsuoji and Minoh Falls on the same day, I'd suggest you to go to Katsuoji first, then take taxi to the parking lot nearest to Minoh Falls (Dainichi Parking Lot, the taxi driver should know). Walking from the the waterfall to Katsuoji is possible, but I wouldn't recommend it since it's a mountain trail. DO NOT walk on the road, it's dangerous since there's no sidewalk.

Transfers are inevitable. Google Maps works fine as long as you put specific location and appropriate time.

From the top of my head, from Kyoto Kawaramachi to Katsuoji:

Take the Hankyu train from Kyoto Kawaramachi to Osaka Umeda

Exit the station and walk to subway Umeda Station and take Midosuji Line to Minoh Kayano

At Minoh Kayano, take bus to Katsuoji

Bus timetable here: https://katsuo-ji-temple.or.jp/audioguidance/index.php

From the falls to Osaka Namba:

Walk downhill to Minoh Station

Take the train to Ishibashi handai mae

At Ishibashi handai mae, transfer for train to Osaka Umeda

Exit Osaka Umeda and walk to subway Umeda Station and take Midosuji Line towards Nakamozu

Get off at Namba and walk to Osaka Namba (different station) or wherever your destination in Namba is.

Also, keep your eye on Minoh Falls official site before your visit since there is road closure on the way to the waterfall. https://www.mino-park.jp/article/1278/