I'll provide my two cents worth on the spliced rafters. While you will find no direct refrence to them in the codes, they are addressed by interpretation of the intent of the code.

R801.2 requires rafters to be 'capable of accomodating all loads imposed'.

R301.1 requires that framing '...all parts thereof, shall be constructed to safely support all loads...in a system that provides a complete load path...'

Further, R301.1.3 states 'When a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise, not conforming to this code, these elements shall be designed in accordance with accepted engineering practice.'

Looking further, back to the Legacy Codes, the SBC covered the problem quite well. 2301.2.1 'The quality and design of wood members and their fastenings used for load supporting purposes shall conform to good engineering practice..'
2301.2.2 'All members shall be framed, anchored, tied and braced so as to develop the strength and rigidity necessary for the purposes for which they are used.'

Based upon questioning 'the ability to accomodate loads imposed', 'ability to safely support all loads', 'exceeding the limits and not conforming', 'braced so as to develop the strength', 'accepted or good engineering practice', and 'strength and rigidity necessary' I require spliced rafters to be supported at the splice down to the structural framing or provide engineering.

I hope this helps.