https://ctext.org/dictionary.pl?if=en&id=12913&remap=gb#s10096477
朝秦楚，莅中国而抚四夷也
As per the translation, it seems like 秦楚 are doing the 朝'ing and the 中国 are doing the 莅'ing, so why do these verbs come before the noun they modify?
I am also having some trouble understanding
以若所为求若所欲
Would this be a correct understanding? But 以 if 若 your desires 所为求 are indeed what you wish 若所欲... (then it's like climbing a tree to find fish)
欲辟土地，朝秦楚，莅中國而撫四夷也
The grammatical subject is hidden (Liang Hui Wang, 梁惠王). What we see are four parallel verb-object constructions that describe Mencius' guess of Liang Hui Wang's desires (王之所大欲).
辟土地: 'to enlarge your territories'
朝秦楚: while normally 朝 as a verb means ‘to meet in court', this is no doubt used in the causative sense (使動用法, see fourth entry here): 'to make (Qin and Chu) meet in (your) court'.
莅中國: 莅 simply means 'to come'. 中國 does not mean China, it refers to the Central Kingdoms (somewhat similar to 中原).
撫四夷: 'to pacify the barbarous tribes on the four boarders'.
You may consult D. C. Lau (1984:21)'s translation too: 'You wish to extend your territory, to enjoy the homage of Ch'in and Ch'u, to rule over the Central Kingdoms and to bring peace to the barbarian tribes on the four boarders.'
以若所為求若所欲
The 所-construction nominalises the verb that follows it. So 所為 means 'deeds' (from 'to do') and 所欲 means 'wants' (from 'to want'). 若 means 'you'. But we see two nouns adjacent to each other in 若所為 and 若所欲. For better understanding, you may add 之 in between, indicating possession: 以若之所為，求若之所欲.
以A求B means to seek B with A.
D. C. Lau: 'Seeking the fulfilment of such an ambition by such means as you employ'
Reference
Lau DC. Mencius. Hong Kong: CUHK Press; 1984.
[朝]秦楚 = [上朝]接見秦國和楚國來的朝臣 = [hold royal court] receiving the officers from Qin and Chu's courts (meaning they are submissive to you)
莅中国 = [莅]於中国 = [offically attend functions] in the middle kingdom
而[抚]四夷也 = and [console/ appease] the barbarian outside the borders (meaning you are the one who speaks for the middle kingdom)
以若所为求若所欲 犹缘木而求鱼也
with your action to seek things that your desire, is like climbing a tree to seek for fish (meaning what you are doing won't work)
若 here means 'your'
Meaning: [3] [pron] you; your
If you have phrases like 朝秦楚，莅中国而抚四夷也 just paste them into Baidu. Someone somewhen has already rendered them in Modern Chinese
曰：
Spake:
“然则王之所大欲可知已，
"Thus the King that which (he) greatly desires (we) can know already,
欲辟土地，
want open (more) land,
朝秦楚，
reign Qin and Chu
莅中国而抚四夷也。
administer (whole of) China and placate the four barbarian (peoples).
1.以若所为求若所欲，
if such way behave if such way desire,
犹缘木而求鱼也。"
like up tree and want fish yeah!
