In order to tackle this, though, we need a complete list of the different mediums, or at least a functional list that will cover most artistic mediums found in the 17th century, at least in Europe - I don't have a strong enough understanding of non-European art forms right now to cover them, but I think they can be encompassed within some of the following categories.
Drawing from Wikipedia, we get the following list, edited for the time period:
Architecture (both building construction and landscaping)
Ceramics (molding and throwing)
Cooking (basic food prep and the creation of spectacular food sculptures)
Drawing (charcoal, etching, oil painting, inkwash painting)
Literature (poetry [Milton's Paradise Lost dates from 1667] and prose novels)
Music (court music, folk music, opera, and liturgical music being our primary categories)
Performing Arts (acting and dance [with court and folk styles])
Sculpture (bone, brass, bronze, glass, ice, stone, wax, and wood)
Fashion as an art form appears to have originated in the 19th c. - prior to that, fashion was dictated by whatever was worn by the royal court, not by the seamstress or tailor - so I'm excluding it from the list.
I feel that we have two broad categories into which we can sort each of these mediums: Experiences and Contemplations.
An Experiential medium is time-dependent, coming down to a single moment in time where the magic happens. Food, Music, and the Performing Arts fall into this category. Experiential artworks catch audience attention very easily, but their effects are more transient.
A Contemplative medium is also time-dependent, in that it requires the audience to spend time observing and interacting with the artwork. Architecture, Ceramics, Drawing, Literature, Painting, and Sculpture are all Contemplations. While these artworks require more initial buy-in from the audience, their effects can be more profound.
While these two categories are helpful in sussing out the kinds of effects to be expected by each medium, each still requires their own list of effects. A bard would choose one of these mediums, as well as a specialty within it (if offered). Bards could create artwork at their level with their specialty, artwork as a bard of 3/4 their level within their medium, and have little to no proficiency in any other medium. If this were Prodigy, I'd have a different skill for each medium, since there is almost no overlap between them.
Here's the first table of magical effects for Architecture. I didn't feel a strong need to separate landscape design from building construction, but some of the effects on this list could easily be typed to one or the other.
|1||While within the constructed space, emotions are calmed due to the pleasing topography and judicious use of the golden ratio|
|2||The constructed space is inherently frustrating and vexing, as all stairs are stumble stairs, the floor is slightly uneven, the ceiling too low, etc.|
|3||Resonant: due to the specifically placed resonating surfaces, all sounds can be head at twice the usual distance. Sound-based magic spells are 50% stronger.|
|4||Echoless: sound-absorbing materials swallow sounds in the area, reducing the volume of all sounds by 50%. Sound-based magic has a 50% chance to fail outright.|
|5||Confusing: the constructed space intentionally confounds one's sense of direction. The probability of getting lost within it is doubled.|
|6||Due to superior irrigation and the correct field geometries, crop yields are increased by 25%. All plants receive this benefit (including plant-like creatures)|
|7||The layout of the area is a holy geometry and repels undead and evil outsiders as a cleric of the bard's level.|
|8||The layout of the area is a perversion of sacred symbols and attracts undead and evil outsiders.|
|9||Somehow, the area is 50% larger on the inside.|
|10||By placing hidden reflective surfaces at precise locations, the entire area is always illuminated by candlelight.|
|11||The area is aligned with the ley lines running underneath the earth, causing perpetual good weather and ample game.|
|12||By subtly cutting across the ley lines with iron and other manufactured materials, the natural energy of the earth has been aborted, drawing fell beasts and bad weather.|
|13||The sun, stars, and moon have been subtly blocked from illuminating the entire area, creating a perpetual, low-grade darkness.|
|14||Fashioned in a series of divine symbols, the entire area acts as a consecrated temple.|
|15||The intentionally open design of the complex facilitates communication with extraplanar entities.|
|16||The complex is a linked network of inverted holy symbols, strengthening the undead, demons, and devils.|
|17||The area features seemingly-impossible feats of architecture and inspires wonder from all who pass by. Productivity is increased by 25%.|
|18||Nationalistic: the construction incorporates symbols and narratives from the local area, strengthening local patriotism.|
|19||The grandeur of the complex inspires volunteers and aid from the local community, who will donate funds and offer additonal laborers in order to be a part of this project.|
|20||The structure is imposing and lends an aura of leadership and power to those who speak from its balconies. Speeches and commands given from the structure are more likely to have an impact upon those who hear them.|
As I mentioned previously, more powerful bards are able to work longer to produce a more powerful work of art. Choosing the same effect multiple times would add to the benefit, increasing the yield by 1/2 each time (so choosing 9 twice would result in an area that is 75% larger on the inside).
Architecture was probably a poor medium to begin with, but we'll go with it. It has a couple of unique challenges - while the time to design it remains unchanged, the whole complex has to be built, a process which (I'm approximating here) would probably take the design time increased by a factor of 10 to complete (construction is slow - stone needs to be quarried, trees need time to grow, etc.) - and a Grandmaster architecture work would be a castle or small city. Thus, I feel that, barring physical destruction of the architectural space, these effects would be permanent.
It also occurs to me that I didn't provide a link between my tiers and typical D&D levels. I'd expect Novices to be bards without levels (and thus unable to take advantage of this system).
Levels 1-2: Apprentice
Levels 3-6: Journeyman
Levels 7-11: Specialist
Levels 12-17: Master
Levels 18+: Grandmaster
It's a rough translation, but close enough to convey the idea.
I'll post the remaining tables as I finish them.