I'm not sure what equipment or options LF3 brings to the table, but here is a bit of extra information on the topic:
18pts: Steal Points: Reward from the Thieves' Guild, LF1 exclusive; Chapter 3.
8-12pts: Primo Hat: 'Head' armor for Cindy, LF1 exclusive.
1-3pts: Luck Ring: 'Other' equipment for Random
The Primo Hat and Luck ring offer a random bonus. The two together will give you anywhere from 9-15 thievery on any given attempt, so you'll need to try a few times to get the max result. To reach 65 thievery though, you'll need to boost Cindy's SP stat considerably. Equip the best SP+ items you have on Cindy, but stick with the 'Fast Shoes' 'other' equipment if you have it; it's better in the long run. Inflict the werewolf condition on her first, using Brussian's 'Werewolf Bite' skill (Learned at Lv. 56). Then inflict her with the energy burn condition using Tarabulla's 'Energy Burn' skill.
Assuming you have the steal points from LF1, and get the full 15 thievery bonus from the Primo Hat and Luck Ring; Cindy will need ~2740+SP to succeed. Without the primo hat, but still using the Luck Ring, Cindy will need ~3900+SP to succeed. These numbers are approximate though, and may vary. Cindy will ideally need to be level 50+ for this. Although you can also use some of your stat boosting items to buffer her speed stat.
The short version is Cindy needs to be level 50 (On normal difficulty) with every bonus, the absolute best equipment possible (as of LF2), and energy burn and werewolf bite to succeed in LF2. Or you can use permanent speed boosting items on her to reach 65 steal earlier than level 50.
Laxius Force 3 may have added extra equipment for Cindy that gives a larger flat speed boost, or conveys a status effect with a speed boost, allowing her to reach 65 thievery at a lower level than 50 perhaps? Of note, the Tyrant mask gives a big speed boost if you don't have the Primo Hat, and either the fast shoes or capul ring may still be your best accessory option? Beyond that, you might check what new LF3 weapons are available (Better than Linderitz Scimitar), and especially check her new shield and armor options as she had very few good options in LF2 for those two equipment slots.