Alright, before I start I must say I got this ideas from many other F2P games like LoL, Dota, and CS:GO. Lilithgame should add cosmetics into the game for a few reason why: These customization can come inform of heroes' skins, unit model skins, mount skins and spell effect.
When such customisation is added into the game, it gives player the ability to personalise themselves with these adds-on and make them stand out unique amoung many other commanders. If the price is right, players would definitely want to purchase these skins to look "cool" and stand out in the game.
Source of Revenue
For many f2p games, cosmetic adds-on are a huge success with players because it give the benefits of improved customisation(see above). If Lilithgame can make the cosmetics and skins cheap enough, it can draw many players to spend sums on them. Currently, most of Lilthgame's revenue comes from heroes purchase and patrons which usually falls off after a month or so when servers mature and becomes old. In this context, cosmetics and skins can be used by developers to earn extra source of revenue from the older servers instead of relying on opening a new server almost everyday.
This might seem a bit far-fetch, but I'll try to explain my reasoning as to why cosmetics and skins can solve the issue of unbalanced Jacques
Currently, most of Lilithgame's revenue comes from the purchase of heroes, especially 2nd purchased heroes and thereafter. With cosmetics and skins as an addition source of revenue, Lilithgame can rely less on hero purchases which probably makes up the bulk of their revenue. Relying less on heroes for their revenue, allows the developers more room to make REAL balance changes to heroes without cutting their own source of income. This is when the nerfing of Jacques comes in. Jacques is undoubtedly gamebreaking and I would not further why(there are many threads out there), and most player's first hero purchased would definitely be Jacques, from the newer servers 100 onward+chinese servers this is almost certainly true. The same goes for most player's second hero purchase without Jacques. Due to the unbalanced nature of jacques, it is a must-have for the experienced players as they understand the gamebreaking power of Jacques. If Lilithgame were to nerf Jacques, it may result in less people buying a second hero as usually one hero is enough if no obvious gamebreaking power hero exist. And this will hurt Lililthgame's income and probably explain why Lilithgame is unwilling to nerf Jacques to protect their main source of revenueincome. Now, if cosmetics and skins can offset the revenue foregone to nerfing Jacques, will Lilithgame nerf Jacques and put an end to bronze dueling and raiding?
Off course, the last point may be invalid should any of the the premise stated is false(eg. Lilithgame refusing to nerf jacques due to fear of revenue loss). However the first 2 point still stands true. This gives the game more content and helps the dev with and additional source of income.